/*------------------------------------------------------------------------- * * deparse.c * Query deparser for postgres_fdw * * This file includes functions that examine query WHERE clauses to see * whether they're safe to send to the remote server for execution, as * well as functions to construct the query text to be sent. The latter * functionality is annoyingly duplicative of ruleutils.c, but there are * enough special considerations that it seems best to keep this separate. * One saving grace is that we only need deparse logic for node types that * we consider safe to send. * * We assume that the remote session's search_path is exactly "pg_catalog", * and thus we need schema-qualify all and only names outside pg_catalog. * * We do not consider that it is ever safe to send COLLATE expressions to * the remote server: it might not have the same collation names we do. * (Later we might consider it safe to send COLLATE "C", but even that would * fail on old remote servers.) An expression is considered safe to send * only if all operator/function input collations used in it are traceable to * Var(s) of the foreign table. That implies that if the remote server gets * a different answer than we do, the foreign table's columns are not marked * with collations that match the remote table's columns, which we can * consider to be user error. * * Portions Copyright (c) 2012-2023, PostgreSQL Global Development Group * * IDENTIFICATION * contrib/postgres_fdw/deparse.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/htup_details.h" #include "access/sysattr.h" #include "access/table.h" #include "catalog/pg_aggregate.h" #include "catalog/pg_authid.h" #include "catalog/pg_collation.h" #include "catalog/pg_namespace.h" #include "catalog/pg_operator.h" #include "catalog/pg_opfamily.h" #include "catalog/pg_proc.h" #include "catalog/pg_ts_config.h" #include "catalog/pg_ts_dict.h" #include "catalog/pg_type.h" #include "commands/defrem.h" #include "nodes/makefuncs.h" #include "nodes/nodeFuncs.h" #include "nodes/plannodes.h" #include "optimizer/optimizer.h" #include "optimizer/prep.h" #include "optimizer/tlist.h" #include "parser/parsetree.h" #include "postgres_fdw.h" #include "utils/builtins.h" #include "utils/lsyscache.h" #include "utils/rel.h" #include "utils/syscache.h" #include "utils/typcache.h" #include "commands/tablecmds.h" /* * Global context for foreign_expr_walker's search of an expression tree. */ typedef struct foreign_glob_cxt { PlannerInfo *root; /* global planner state */ RelOptInfo *foreignrel; /* the foreign relation we are planning for */ Relids relids; /* relids of base relations in the underlying * scan */ } foreign_glob_cxt; /* * Local (per-tree-level) context for foreign_expr_walker's search. * This is concerned with identifying collations used in the expression. */ typedef enum { FDW_COLLATE_NONE, /* expression is of a noncollatable type, or * it has default collation that is not * traceable to a foreign Var */ FDW_COLLATE_SAFE, /* collation derives from a foreign Var */ FDW_COLLATE_UNSAFE /* collation is non-default and derives from * something other than a foreign Var */ } FDWCollateState; typedef struct foreign_loc_cxt { Oid collation; /* OID of current collation, if any */ FDWCollateState state; /* state of current collation choice */ } foreign_loc_cxt; /* * Context for deparseExpr */ typedef struct deparse_expr_cxt { PlannerInfo *root; /* global planner state */ RelOptInfo *foreignrel; /* the foreign relation we are planning for */ RelOptInfo *scanrel; /* the underlying scan relation. Same as * foreignrel, when that represents a join or * a base relation. */ StringInfo buf; /* output buffer to append to */ List **params_list; /* exprs that will become remote Params */ } deparse_expr_cxt; #define REL_ALIAS_PREFIX "r" /* Handy macro to add relation name qualification */ #define ADD_REL_QUALIFIER(buf, varno) \ appendStringInfo((buf), "%s%d.", REL_ALIAS_PREFIX, (varno)) #define SUBQUERY_REL_ALIAS_PREFIX "s" #define SUBQUERY_COL_ALIAS_PREFIX "c" /* * Functions to determine whether an expression can be evaluated safely on * remote server. */ static bool foreign_expr_walker(Node *node, foreign_glob_cxt *glob_cxt, foreign_loc_cxt *outer_cxt, foreign_loc_cxt *case_arg_cxt); static char *deparse_type_name(Oid type_oid, int32 typemod); /* * Functions to construct string representation of a node tree. */ static void deparseTargetList(StringInfo buf, RangeTblEntry *rte, Index rtindex, Relation rel, bool is_returning, Bitmapset *attrs_used, bool qualify_col, List **retrieved_attrs); static void deparseExplicitTargetList(List *tlist, bool is_returning, List **retrieved_attrs, deparse_expr_cxt *context); static void deparseSubqueryTargetList(deparse_expr_cxt *context); static void deparseReturningList(StringInfo buf, RangeTblEntry *rte, Index rtindex, Relation rel, bool trig_after_row, List *withCheckOptionList, List *returningList, List **retrieved_attrs); static void deparseColumnRef(StringInfo buf, int varno, int varattno, RangeTblEntry *rte, bool qualify_col); static void deparseRelation(StringInfo buf, Relation rel); static void deparseExpr(Expr *node, deparse_expr_cxt *context); static void deparseVar(Var *node, deparse_expr_cxt *context); static void deparseConst(Const *node, deparse_expr_cxt *context, int showtype); static void deparseParam(Param *node, deparse_expr_cxt *context); static void deparseSubscriptingRef(SubscriptingRef *node, deparse_expr_cxt *context); static void deparseFuncExpr(FuncExpr *node, deparse_expr_cxt *context); static void deparseOpExpr(OpExpr *node, deparse_expr_cxt *context); static bool isPlainForeignVar(Expr *node, deparse_expr_cxt *context); static void deparseOperatorName(StringInfo buf, Form_pg_operator opform); static void deparseDistinctExpr(DistinctExpr *node, deparse_expr_cxt *context); static void deparseScalarArrayOpExpr(ScalarArrayOpExpr *node, deparse_expr_cxt *context); static void deparseRelabelType(RelabelType *node, deparse_expr_cxt *context); static void deparseBoolExpr(BoolExpr *node, deparse_expr_cxt *context); static void deparseNullTest(NullTest *node, deparse_expr_cxt *context); static void deparseCaseExpr(CaseExpr *node, deparse_expr_cxt *context); static void deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context); static void printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod, deparse_expr_cxt *context); static void printRemotePlaceholder(Oid paramtype, int32 paramtypmod, deparse_expr_cxt *context); static void deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs, deparse_expr_cxt *context); static void deparseLockingClause(deparse_expr_cxt *context); static void appendOrderByClause(List *pathkeys, bool has_final_sort, deparse_expr_cxt *context); static void appendLimitClause(deparse_expr_cxt *context); static void appendConditions(List *exprs, deparse_expr_cxt *context); static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel, bool use_alias, Index ignore_rel, List **ignore_conds, List **params_list); static void deparseFromExpr(List *quals, deparse_expr_cxt *context); static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel, bool make_subquery, Index ignore_rel, List **ignore_conds, List **params_list); static void deparseAggref(Aggref *node, deparse_expr_cxt *context); static void appendGroupByClause(List *tlist, deparse_expr_cxt *context); static void appendOrderBySuffix(Oid sortop, Oid sortcoltype, bool nulls_first, deparse_expr_cxt *context); static void appendAggOrderBy(List *orderList, List *targetList, deparse_expr_cxt *context); static void appendFunctionName(Oid funcid, deparse_expr_cxt *context); static Node *deparseSortGroupClause(Index ref, List *tlist, bool force_colno, deparse_expr_cxt *context); /* * Helper functions */ static bool is_subquery_var(Var *node, RelOptInfo *foreignrel, int *relno, int *colno); static void get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel, int *relno, int *colno); /* * Examine each qual clause in input_conds, and classify them into two groups, * which are returned as two lists: * - remote_conds contains expressions that can be evaluated remotely * - local_conds contains expressions that can't be evaluated remotely */ void classifyConditions(PlannerInfo *root, RelOptInfo *baserel, List *input_conds, List **remote_conds, List **local_conds) { ListCell *lc; *remote_conds = NIL; *local_conds = NIL; foreach(lc, input_conds) { RestrictInfo *ri = lfirst_node(RestrictInfo, lc); if (is_foreign_expr(root, baserel, ri->clause)) *remote_conds = lappend(*remote_conds, ri); else *local_conds = lappend(*local_conds, ri); } } /* * Returns true if given expr is safe to evaluate on the foreign server. */ bool is_foreign_expr(PlannerInfo *root, RelOptInfo *baserel, Expr *expr) { foreign_glob_cxt glob_cxt; foreign_loc_cxt loc_cxt; PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) (baserel->fdw_private); /* * Check that the expression consists of nodes that are safe to execute * remotely. */ glob_cxt.root = root; glob_cxt.foreignrel = baserel; /* * For an upper relation, use relids from its underneath scan relation, * because the upperrel's own relids currently aren't set to anything * meaningful by the core code. For other relation, use their own relids. */ if (IS_UPPER_REL(baserel)) glob_cxt.relids = fpinfo->outerrel->relids; else glob_cxt.relids = baserel->relids; loc_cxt.collation = InvalidOid; loc_cxt.state = FDW_COLLATE_NONE; if (!foreign_expr_walker((Node *) expr, &glob_cxt, &loc_cxt, NULL)) return false; /* * If the expression has a valid collation that does not arise from a * foreign var, the expression can not be sent over. */ if (loc_cxt.state == FDW_COLLATE_UNSAFE) return false; /* * An expression which includes any mutable functions can't be sent over * because its result is not stable. For example, sending now() remote * side could cause confusion from clock offsets. Future versions might * be able to make this choice with more granularity. (We check this last * because it requires a lot of expensive catalog lookups.) */ if (contain_mutable_functions((Node *) expr)) return false; /* OK to evaluate on the remote server */ return true; } /* * Check if expression is safe to execute remotely, and return true if so. * * In addition, *outer_cxt is updated with collation information. * * case_arg_cxt is NULL if this subexpression is not inside a CASE-with-arg. * Otherwise, it points to the collation info derived from the arg expression, * which must be consulted by any CaseTestExpr. * * We must check that the expression contains only node types we can deparse, * that all types/functions/operators are safe to send (they are "shippable"), * and that all collations used in the expression derive from Vars of the * foreign table. Because of the latter, the logic is pretty close to * assign_collations_walker() in parse_collate.c, though we can assume here * that the given expression is valid. Note function mutability is not * currently considered here. */ static bool foreign_expr_walker(Node *node, foreign_glob_cxt *glob_cxt, foreign_loc_cxt *outer_cxt, foreign_loc_cxt *case_arg_cxt) { bool check_type = true; PgFdwRelationInfo *fpinfo; foreign_loc_cxt inner_cxt; Oid collation; FDWCollateState state; /* Need do nothing for empty subexpressions */ if (node == NULL) return true; /* May need server info from baserel's fdw_private struct */ fpinfo = (PgFdwRelationInfo *) (glob_cxt->foreignrel->fdw_private); /* Set up inner_cxt for possible recursion to child nodes */ inner_cxt.collation = InvalidOid; inner_cxt.state = FDW_COLLATE_NONE; switch (nodeTag(node)) { case T_Var: { Var *var = (Var *) node; /* * If the Var is from the foreign table, we consider its * collation (if any) safe to use. If it is from another * table, we treat its collation the same way as we would a * Param's collation, ie it's not safe for it to have a * non-default collation. */ if (bms_is_member(var->varno, glob_cxt->relids) && var->varlevelsup == 0) { /* Var belongs to foreign table */ /* * System columns other than ctid should not be sent to * the remote, since we don't make any effort to ensure * that local and remote values match (tableoid, in * particular, almost certainly doesn't match). */ if (var->varattno < 0 && var->varattno != SelfItemPointerAttributeNumber) return false; /* Else check the collation */ collation = var->varcollid; state = OidIsValid(collation) ? FDW_COLLATE_SAFE : FDW_COLLATE_NONE; } else { /* Var belongs to some other table */ collation = var->varcollid; if (collation == InvalidOid || collation == DEFAULT_COLLATION_OID) { /* * It's noncollatable, or it's safe to combine with a * collatable foreign Var, so set state to NONE. */ state = FDW_COLLATE_NONE; } else { /* * Do not fail right away, since the Var might appear * in a collation-insensitive context. */ state = FDW_COLLATE_UNSAFE; } } } break; case T_Const: { Const *c = (Const *) node; /* * Constants of regproc and related types can't be shipped * unless the referenced object is shippable. But NULL's ok. * (See also the related code in dependency.c.) */ if (!c->constisnull) { switch (c->consttype) { case REGPROCOID: case REGPROCEDUREOID: if (!is_shippable(DatumGetObjectId(c->constvalue), ProcedureRelationId, fpinfo)) return false; break; case REGOPEROID: case REGOPERATOROID: if (!is_shippable(DatumGetObjectId(c->constvalue), OperatorRelationId, fpinfo)) return false; break; case REGCLASSOID: if (!is_shippable(DatumGetObjectId(c->constvalue), RelationRelationId, fpinfo)) return false; break; case REGTYPEOID: if (!is_shippable(DatumGetObjectId(c->constvalue), TypeRelationId, fpinfo)) return false; break; case REGCOLLATIONOID: if (!is_shippable(DatumGetObjectId(c->constvalue), CollationRelationId, fpinfo)) return false; break; case REGCONFIGOID: /* * For text search objects only, we weaken the * normal shippability criterion to allow all OIDs * below FirstNormalObjectId. Without this, none * of the initdb-installed TS configurations would * be shippable, which would be quite annoying. */ if (DatumGetObjectId(c->constvalue) >= FirstNormalObjectId && !is_shippable(DatumGetObjectId(c->constvalue), TSConfigRelationId, fpinfo)) return false; break; case REGDICTIONARYOID: if (DatumGetObjectId(c->constvalue) >= FirstNormalObjectId && !is_shippable(DatumGetObjectId(c->constvalue), TSDictionaryRelationId, fpinfo)) return false; break; case REGNAMESPACEOID: if (!is_shippable(DatumGetObjectId(c->constvalue), NamespaceRelationId, fpinfo)) return false; break; case REGROLEOID: if (!is_shippable(DatumGetObjectId(c->constvalue), AuthIdRelationId, fpinfo)) return false; break; } } /* * If the constant has nondefault collation, either it's of a * non-builtin type, or it reflects folding of a CollateExpr. * It's unsafe to send to the remote unless it's used in a * non-collation-sensitive context. */ collation = c->constcollid; if (collation == InvalidOid || collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; case T_Param: { Param *p = (Param *) node; /* * If it's a MULTIEXPR Param, punt. We can't tell from here * whether the referenced sublink/subplan contains any remote * Vars; if it does, handling that is too complicated to * consider supporting at present. Fortunately, MULTIEXPR * Params are not reduced to plain PARAM_EXEC until the end of * planning, so we can easily detect this case. (Normal * PARAM_EXEC Params are safe to ship because their values * come from somewhere else in the plan tree; but a MULTIEXPR * references a sub-select elsewhere in the same targetlist, * so we'd be on the hook to evaluate it somehow if we wanted * to handle such cases as direct foreign updates.) */ if (p->paramkind == PARAM_MULTIEXPR) return false; /* * Collation rule is same as for Consts and non-foreign Vars. */ collation = p->paramcollid; if (collation == InvalidOid || collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; case T_SubscriptingRef: { SubscriptingRef *sr = (SubscriptingRef *) node; /* Assignment should not be in restrictions. */ if (sr->refassgnexpr != NULL) return false; /* * Recurse into the remaining subexpressions. The container * subscripts will not affect collation of the SubscriptingRef * result, so do those first and reset inner_cxt afterwards. */ if (!foreign_expr_walker((Node *) sr->refupperindexpr, glob_cxt, &inner_cxt, case_arg_cxt)) return false; inner_cxt.collation = InvalidOid; inner_cxt.state = FDW_COLLATE_NONE; if (!foreign_expr_walker((Node *) sr->reflowerindexpr, glob_cxt, &inner_cxt, case_arg_cxt)) return false; inner_cxt.collation = InvalidOid; inner_cxt.state = FDW_COLLATE_NONE; if (!foreign_expr_walker((Node *) sr->refexpr, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* * Container subscripting typically yields same collation as * refexpr's, but in case it doesn't, use same logic as for * function nodes. */ collation = sr->refcollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else if (collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; case T_FuncExpr: { FuncExpr *fe = (FuncExpr *) node; /* * If function used by the expression is not shippable, it * can't be sent to remote because it might have incompatible * semantics on remote side. */ if (!is_shippable(fe->funcid, ProcedureRelationId, fpinfo)) return false; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) fe->args, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* * If function's input collation is not derived from a foreign * Var, it can't be sent to remote. */ if (fe->inputcollid == InvalidOid) /* OK, inputs are all noncollatable */ ; else if (inner_cxt.state != FDW_COLLATE_SAFE || fe->inputcollid != inner_cxt.collation) return false; /* * Detect whether node is introducing a collation not derived * from a foreign Var. (If so, we just mark it unsafe for now * rather than immediately returning false, since the parent * node might not care.) */ collation = fe->funccollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else if (collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; case T_OpExpr: case T_DistinctExpr: /* struct-equivalent to OpExpr */ { OpExpr *oe = (OpExpr *) node; /* * Similarly, only shippable operators can be sent to remote. * (If the operator is shippable, we assume its underlying * function is too.) */ if (!is_shippable(oe->opno, OperatorRelationId, fpinfo)) return false; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) oe->args, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* * If operator's input collation is not derived from a foreign * Var, it can't be sent to remote. */ if (oe->inputcollid == InvalidOid) /* OK, inputs are all noncollatable */ ; else if (inner_cxt.state != FDW_COLLATE_SAFE || oe->inputcollid != inner_cxt.collation) return false; /* Result-collation handling is same as for functions */ collation = oe->opcollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else if (collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; case T_ScalarArrayOpExpr: { ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node; /* * Again, only shippable operators can be sent to remote. */ if (!is_shippable(oe->opno, OperatorRelationId, fpinfo)) return false; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) oe->args, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* * If operator's input collation is not derived from a foreign * Var, it can't be sent to remote. */ if (oe->inputcollid == InvalidOid) /* OK, inputs are all noncollatable */ ; else if (inner_cxt.state != FDW_COLLATE_SAFE || oe->inputcollid != inner_cxt.collation) return false; /* Output is always boolean and so noncollatable. */ collation = InvalidOid; state = FDW_COLLATE_NONE; } break; case T_RelabelType: { RelabelType *r = (RelabelType *) node; /* * Recurse to input subexpression. */ if (!foreign_expr_walker((Node *) r->arg, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* * RelabelType must not introduce a collation not derived from * an input foreign Var (same logic as for a real function). */ collation = r->resultcollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else if (collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; case T_BoolExpr: { BoolExpr *b = (BoolExpr *) node; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) b->args, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* Output is always boolean and so noncollatable. */ collation = InvalidOid; state = FDW_COLLATE_NONE; } break; case T_NullTest: { NullTest *nt = (NullTest *) node; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) nt->arg, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* Output is always boolean and so noncollatable. */ collation = InvalidOid; state = FDW_COLLATE_NONE; } break; case T_CaseExpr: { CaseExpr *ce = (CaseExpr *) node; foreign_loc_cxt arg_cxt; foreign_loc_cxt tmp_cxt; ListCell *lc; /* * Recurse to CASE's arg expression, if any. Its collation * has to be saved aside for use while examining CaseTestExprs * within the WHEN expressions. */ arg_cxt.collation = InvalidOid; arg_cxt.state = FDW_COLLATE_NONE; if (ce->arg) { if (!foreign_expr_walker((Node *) ce->arg, glob_cxt, &arg_cxt, case_arg_cxt)) return false; } /* Examine the CaseWhen subexpressions. */ foreach(lc, ce->args) { CaseWhen *cw = lfirst_node(CaseWhen, lc); if (ce->arg) { /* * In a CASE-with-arg, the parser should have produced * WHEN clauses of the form "CaseTestExpr = RHS", * possibly with an implicit coercion inserted above * the CaseTestExpr. However in an expression that's * been through the optimizer, the WHEN clause could * be almost anything (since the equality operator * could have been expanded into an inline function). * In such cases forbid pushdown, because * deparseCaseExpr can't handle it. */ Node *whenExpr = (Node *) cw->expr; List *opArgs; if (!IsA(whenExpr, OpExpr)) return false; opArgs = ((OpExpr *) whenExpr)->args; if (list_length(opArgs) != 2 || !IsA(strip_implicit_coercions(linitial(opArgs)), CaseTestExpr)) return false; } /* * Recurse to WHEN expression, passing down the arg info. * Its collation doesn't affect the result (really, it * should be boolean and thus not have a collation). */ tmp_cxt.collation = InvalidOid; tmp_cxt.state = FDW_COLLATE_NONE; if (!foreign_expr_walker((Node *) cw->expr, glob_cxt, &tmp_cxt, &arg_cxt)) return false; /* Recurse to THEN expression. */ if (!foreign_expr_walker((Node *) cw->result, glob_cxt, &inner_cxt, case_arg_cxt)) return false; } /* Recurse to ELSE expression. */ if (!foreign_expr_walker((Node *) ce->defresult, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* * Detect whether node is introducing a collation not derived * from a foreign Var. (If so, we just mark it unsafe for now * rather than immediately returning false, since the parent * node might not care.) This is the same as for function * nodes, except that the input collation is derived from only * the THEN and ELSE subexpressions. */ collation = ce->casecollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else if (collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; case T_CaseTestExpr: { CaseTestExpr *c = (CaseTestExpr *) node; /* Punt if we seem not to be inside a CASE arg WHEN. */ if (!case_arg_cxt) return false; /* * Otherwise, any nondefault collation attached to the * CaseTestExpr node must be derived from foreign Var(s) in * the CASE arg. */ collation = c->collation; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (case_arg_cxt->state == FDW_COLLATE_SAFE && collation == case_arg_cxt->collation) state = FDW_COLLATE_SAFE; else if (collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; case T_ArrayExpr: { ArrayExpr *a = (ArrayExpr *) node; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) a->elements, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* * ArrayExpr must not introduce a collation not derived from * an input foreign Var (same logic as for a function). */ collation = a->array_collid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else if (collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; case T_List: { List *l = (List *) node; ListCell *lc; /* * Recurse to component subexpressions. */ foreach(lc, l) { if (!foreign_expr_walker((Node *) lfirst(lc), glob_cxt, &inner_cxt, case_arg_cxt)) return false; } /* * When processing a list, collation state just bubbles up * from the list elements. */ collation = inner_cxt.collation; state = inner_cxt.state; /* Don't apply exprType() to the list. */ check_type = false; } break; case T_Aggref: { Aggref *agg = (Aggref *) node; ListCell *lc; /* Not safe to pushdown when not in grouping context */ if (!IS_UPPER_REL(glob_cxt->foreignrel)) return false; /* Only non-split aggregates are pushable. */ if (agg->aggsplit != AGGSPLIT_SIMPLE) return false; /* As usual, it must be shippable. */ if (!is_shippable(agg->aggfnoid, ProcedureRelationId, fpinfo)) return false; /* * Recurse to input args. aggdirectargs, aggorder and * aggdistinct are all present in args, so no need to check * their shippability explicitly. */ foreach(lc, agg->args) { Node *n = (Node *) lfirst(lc); /* If TargetEntry, extract the expression from it */ if (IsA(n, TargetEntry)) { TargetEntry *tle = (TargetEntry *) n; n = (Node *) tle->expr; } if (!foreign_expr_walker(n, glob_cxt, &inner_cxt, case_arg_cxt)) return false; } /* * For aggorder elements, check whether the sort operator, if * specified, is shippable or not. */ if (agg->aggorder) { foreach(lc, agg->aggorder) { SortGroupClause *srt = (SortGroupClause *) lfirst(lc); Oid sortcoltype; TypeCacheEntry *typentry; TargetEntry *tle; tle = get_sortgroupref_tle(srt->tleSortGroupRef, agg->args); sortcoltype = exprType((Node *) tle->expr); typentry = lookup_type_cache(sortcoltype, TYPECACHE_LT_OPR | TYPECACHE_GT_OPR); /* Check shippability of non-default sort operator. */ if (srt->sortop != typentry->lt_opr && srt->sortop != typentry->gt_opr && !is_shippable(srt->sortop, OperatorRelationId, fpinfo)) return false; } } /* Check aggregate filter */ if (!foreign_expr_walker((Node *) agg->aggfilter, glob_cxt, &inner_cxt, case_arg_cxt)) return false; /* * If aggregate's input collation is not derived from a * foreign Var, it can't be sent to remote. */ if (agg->inputcollid == InvalidOid) /* OK, inputs are all noncollatable */ ; else if (inner_cxt.state != FDW_COLLATE_SAFE || agg->inputcollid != inner_cxt.collation) return false; /* * Detect whether node is introducing a collation not derived * from a foreign Var. (If so, we just mark it unsafe for now * rather than immediately returning false, since the parent * node might not care.) */ collation = agg->aggcollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else if (collation == DEFAULT_COLLATION_OID) state = FDW_COLLATE_NONE; else state = FDW_COLLATE_UNSAFE; } break; default: /* * If it's anything else, assume it's unsafe. This list can be * expanded later, but don't forget to add deparse support below. */ return false; } /* * If result type of given expression is not shippable, it can't be sent * to remote because it might have incompatible semantics on remote side. */ if (check_type && !is_shippable(exprType(node), TypeRelationId, fpinfo)) return false; /* * Now, merge my collation information into my parent's state. */ if (state > outer_cxt->state) { /* Override previous parent state */ outer_cxt->collation = collation; outer_cxt->state = state; } else if (state == outer_cxt->state) { /* Merge, or detect error if there's a collation conflict */ switch (state) { case FDW_COLLATE_NONE: /* Nothing + nothing is still nothing */ break; case FDW_COLLATE_SAFE: if (collation != outer_cxt->collation) { /* * Non-default collation always beats default. */ if (outer_cxt->collation == DEFAULT_COLLATION_OID) { /* Override previous parent state */ outer_cxt->collation = collation; } else if (collation != DEFAULT_COLLATION_OID) { /* * Conflict; show state as indeterminate. We don't * want to "return false" right away, since parent * node might not care about collation. */ outer_cxt->state = FDW_COLLATE_UNSAFE; } } break; case FDW_COLLATE_UNSAFE: /* We're still conflicted ... */ break; } } /* It looks OK */ return true; } /* * Returns true if given expr is something we'd have to send the value of * to the foreign server. * * This should return true when the expression is a shippable node that * deparseExpr would add to context->params_list. Note that we don't care * if the expression *contains* such a node, only whether one appears at top * level. We need this to detect cases where setrefs.c would recognize a * false match between an fdw_exprs item (which came from the params_list) * and an entry in fdw_scan_tlist (which we're considering putting the given * expression into). */ bool is_foreign_param(PlannerInfo *root, RelOptInfo *baserel, Expr *expr) { if (expr == NULL) return false; switch (nodeTag(expr)) { case T_Var: { /* It would have to be sent unless it's a foreign Var */ Var *var = (Var *) expr; PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) (baserel->fdw_private); Relids relids; if (IS_UPPER_REL(baserel)) relids = fpinfo->outerrel->relids; else relids = baserel->relids; if (bms_is_member(var->varno, relids) && var->varlevelsup == 0) return false; /* foreign Var, so not a param */ else return true; /* it'd have to be a param */ break; } case T_Param: /* Params always have to be sent to the foreign server */ return true; default: break; } return false; } /* * Returns true if it's safe to push down the sort expression described by * 'pathkey' to the foreign server. */ bool is_foreign_pathkey(PlannerInfo *root, RelOptInfo *baserel, PathKey *pathkey) { EquivalenceClass *pathkey_ec = pathkey->pk_eclass; PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) baserel->fdw_private; /* * is_foreign_expr would detect volatile expressions as well, but checking * ec_has_volatile here saves some cycles. */ if (pathkey_ec->ec_has_volatile) return false; /* can't push down the sort if the pathkey's opfamily is not shippable */ if (!is_shippable(pathkey->pk_opfamily, OperatorFamilyRelationId, fpinfo)) return false; /* can push if a suitable EC member exists */ return (find_em_for_rel(root, pathkey_ec, baserel) != NULL); } /* * Convert type OID + typmod info into a type name we can ship to the remote * server. Someplace else had better have verified that this type name is * expected to be known on the remote end. * * This is almost just format_type_with_typemod(), except that if left to its * own devices, that function will make schema-qualification decisions based * on the local search_path, which is wrong. We must schema-qualify all * type names that are not in pg_catalog. We assume here that built-in types * are all in pg_catalog and need not be qualified; otherwise, qualify. */ static char * deparse_type_name(Oid type_oid, int32 typemod) { bits16 flags = FORMAT_TYPE_TYPEMOD_GIVEN; if (!is_builtin(type_oid)) flags |= FORMAT_TYPE_FORCE_QUALIFY; return format_type_extended(type_oid, typemod, flags); } /* * Build the targetlist for given relation to be deparsed as SELECT clause. * * The output targetlist contains the columns that need to be fetched from the * foreign server for the given relation. If foreignrel is an upper relation, * then the output targetlist can also contain expressions to be evaluated on * foreign server. */ List * build_tlist_to_deparse(RelOptInfo *foreignrel) { List *tlist = NIL; PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private; ListCell *lc; /* * For an upper relation, we have already built the target list while * checking shippability, so just return that. */ if (IS_UPPER_REL(foreignrel)) return fpinfo->grouped_tlist; /* * We require columns specified in foreignrel->reltarget->exprs and those * required for evaluating the local conditions. */ tlist = add_to_flat_tlist(tlist, pull_var_clause((Node *) foreignrel->reltarget->exprs, PVC_RECURSE_PLACEHOLDERS)); foreach(lc, fpinfo->local_conds) { RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc); tlist = add_to_flat_tlist(tlist, pull_var_clause((Node *) rinfo->clause, PVC_RECURSE_PLACEHOLDERS)); } return tlist; } /* * Deparse SELECT statement for given relation into buf. * * tlist contains the list of desired columns to be fetched from foreign server. * For a base relation fpinfo->attrs_used is used to construct SELECT clause, * hence the tlist is ignored for a base relation. * * remote_conds is the list of conditions to be deparsed into the WHERE clause * (or, in the case of upper relations, into the HAVING clause). * * If params_list is not NULL, it receives a list of Params and other-relation * Vars used in the clauses; these values must be transmitted to the remote * server as parameter values. * * If params_list is NULL, we're generating the query for EXPLAIN purposes, * so Params and other-relation Vars should be replaced by dummy values. * * pathkeys is the list of pathkeys to order the result by. * * is_subquery is the flag to indicate whether to deparse the specified * relation as a subquery. * * List of columns selected is returned in retrieved_attrs. */ void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *rel, List *tlist, List *remote_conds, List *pathkeys, bool has_final_sort, bool has_limit, bool is_subquery, List **retrieved_attrs, List **params_list) { deparse_expr_cxt context; PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private; List *quals; /* * We handle relations for foreign tables, joins between those and upper * relations. */ Assert(IS_JOIN_REL(rel) || IS_SIMPLE_REL(rel) || IS_UPPER_REL(rel)); /* Fill portions of context common to upper, join and base relation */ context.buf = buf; context.root = root; context.foreignrel = rel; context.scanrel = IS_UPPER_REL(rel) ? fpinfo->outerrel : rel; context.params_list = params_list; /* Construct SELECT clause */ deparseSelectSql(tlist, is_subquery, retrieved_attrs, &context); /* * For upper relations, the WHERE clause is built from the remote * conditions of the underlying scan relation; otherwise, we can use the * supplied list of remote conditions directly. */ if (IS_UPPER_REL(rel)) { PgFdwRelationInfo *ofpinfo; ofpinfo = (PgFdwRelationInfo *) fpinfo->outerrel->fdw_private; quals = ofpinfo->remote_conds; } else quals = remote_conds; /* Construct FROM and WHERE clauses */ deparseFromExpr(quals, &context); if (IS_UPPER_REL(rel)) { /* Append GROUP BY clause */ appendGroupByClause(tlist, &context); /* Append HAVING clause */ if (remote_conds) { appendStringInfoString(buf, " HAVING "); appendConditions(remote_conds, &context); } } /* Add ORDER BY clause if we found any useful pathkeys */ if (pathkeys) appendOrderByClause(pathkeys, has_final_sort, &context); /* Add LIMIT clause if necessary */ if (has_limit) appendLimitClause(&context); /* Add any necessary FOR UPDATE/SHARE. */ deparseLockingClause(&context); } /* * Construct a simple SELECT statement that retrieves desired columns * of the specified foreign table, and append it to "buf". The output * contains just "SELECT ... ". * * We also create an integer List of the columns being retrieved, which is * returned to *retrieved_attrs, unless we deparse the specified relation * as a subquery. * * tlist is the list of desired columns. is_subquery is the flag to * indicate whether to deparse the specified relation as a subquery. * Read prologue of deparseSelectStmtForRel() for details. */ static void deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs, deparse_expr_cxt *context) { StringInfo buf = context->buf; RelOptInfo *foreignrel = context->foreignrel; PlannerInfo *root = context->root; PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private; /* * Construct SELECT list */ appendStringInfoString(buf, "SELECT "); if (is_subquery) { /* * For a relation that is deparsed as a subquery, emit expressions * specified in the relation's reltarget. Note that since this is for * the subquery, no need to care about *retrieved_attrs. */ deparseSubqueryTargetList(context); } else if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel)) { /* * For a join or upper relation the input tlist gives the list of * columns required to be fetched from the foreign server. */ deparseExplicitTargetList(tlist, false, retrieved_attrs, context); } else { /* * For a base relation fpinfo->attrs_used gives the list of columns * required to be fetched from the foreign server. */ RangeTblEntry *rte = planner_rt_fetch(foreignrel->relid, root); /* * Core code already has some lock on each rel being planned, so we * can use NoLock here. */ Relation rel = table_open(rte->relid, NoLock); deparseTargetList(buf, rte, foreignrel->relid, rel, false, fpinfo->attrs_used, false, retrieved_attrs); table_close(rel, NoLock); } } /* * Construct a FROM clause and, if needed, a WHERE clause, and append those to * "buf". * * quals is the list of clauses to be included in the WHERE clause. * (These may or may not include RestrictInfo decoration.) */ static void deparseFromExpr(List *quals, deparse_expr_cxt *context) { StringInfo buf = context->buf; RelOptInfo *scanrel = context->scanrel; /* For upper relations, scanrel must be either a joinrel or a baserel */ Assert(!IS_UPPER_REL(context->foreignrel) || IS_JOIN_REL(scanrel) || IS_SIMPLE_REL(scanrel)); /* Construct FROM clause */ appendStringInfoString(buf, " FROM "); deparseFromExprForRel(buf, context->root, scanrel, (bms_membership(scanrel->relids) == BMS_MULTIPLE), (Index) 0, NULL, context->params_list); /* Construct WHERE clause */ if (quals != NIL) { appendStringInfoString(buf, " WHERE "); appendConditions(quals, context); } } /* * Emit a target list that retrieves the columns specified in attrs_used. * This is used for both SELECT and RETURNING targetlists; the is_returning * parameter is true only for a RETURNING targetlist. * * The tlist text is appended to buf, and we also create an integer List * of the columns being retrieved, which is returned to *retrieved_attrs. * * If qualify_col is true, add relation alias before the column name. */ static void deparseTargetList(StringInfo buf, RangeTblEntry *rte, Index rtindex, Relation rel, bool is_returning, Bitmapset *attrs_used, bool qualify_col, List **retrieved_attrs) { TupleDesc tupdesc = RelationGetDescr(rel); bool have_wholerow; bool first; int i; *retrieved_attrs = NIL; /* If there's a whole-row reference, we'll need all the columns. */ have_wholerow = bms_is_member(0 - FirstLowInvalidHeapAttributeNumber, attrs_used); first = true; for (i = 1; i <= tupdesc->natts; i++) { Form_pg_attribute attr = TupleDescAttr(tupdesc, i - 1); /* Ignore dropped attributes. */ if (attr->attisdropped) continue; if (have_wholerow || bms_is_member(i - FirstLowInvalidHeapAttributeNumber, attrs_used)) { if (!first) appendStringInfoString(buf, ", "); else if (is_returning) appendStringInfoString(buf, " RETURNING "); first = false; deparseColumnRef(buf, rtindex, i, rte, qualify_col); *retrieved_attrs = lappend_int(*retrieved_attrs, i); } } /* * Add ctid if needed. We currently don't support retrieving any other * system columns. */ if (bms_is_member(SelfItemPointerAttributeNumber - FirstLowInvalidHeapAttributeNumber, attrs_used)) { if (!first) appendStringInfoString(buf, ", "); else if (is_returning) appendStringInfoString(buf, " RETURNING "); first = false; if (qualify_col) ADD_REL_QUALIFIER(buf, rtindex); appendStringInfoString(buf, "ctid"); *retrieved_attrs = lappend_int(*retrieved_attrs, SelfItemPointerAttributeNumber); } /* Don't generate bad syntax if no undropped columns */ if (first && !is_returning) appendStringInfoString(buf, "NULL"); } /* * Deparse the appropriate locking clause (FOR UPDATE or FOR SHARE) for a * given relation (context->scanrel). */ static void deparseLockingClause(deparse_expr_cxt *context) { StringInfo buf = context->buf; PlannerInfo *root = context->root; RelOptInfo *rel = context->scanrel; PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private; int relid = -1; while ((relid = bms_next_member(rel->relids, relid)) >= 0) { /* * Ignore relation if it appears in a lower subquery. Locking clause * for such a relation is included in the subquery if necessary. */ if (bms_is_member(relid, fpinfo->lower_subquery_rels)) continue; /* * Add FOR UPDATE/SHARE if appropriate. We apply locking during the * initial row fetch, rather than later on as is done for local * tables. The extra roundtrips involved in trying to duplicate the * local semantics exactly don't seem worthwhile (see also comments * for RowMarkType). * * Note: because we actually run the query as a cursor, this assumes * that DECLARE CURSOR ... FOR UPDATE is supported, which it isn't * before 8.3. */ if (bms_is_member(relid, root->all_result_relids) && (root->parse->commandType == CMD_UPDATE || root->parse->commandType == CMD_DELETE)) { /* Relation is UPDATE/DELETE target, so use FOR UPDATE */ appendStringInfoString(buf, " FOR UPDATE"); /* Add the relation alias if we are here for a join relation */ if (IS_JOIN_REL(rel)) appendStringInfo(buf, " OF %s%d", REL_ALIAS_PREFIX, relid); } else { PlanRowMark *rc = get_plan_rowmark(root->rowMarks, relid); if (rc) { /* * Relation is specified as a FOR UPDATE/SHARE target, so * handle that. (But we could also see LCS_NONE, meaning this * isn't a target relation after all.) * * For now, just ignore any [NO] KEY specification, since (a) * it's not clear what that means for a remote table that we * don't have complete information about, and (b) it wouldn't * work anyway on older remote servers. Likewise, we don't * worry about NOWAIT. */ switch (rc->strength) { case LCS_NONE: /* No locking needed */ break; case LCS_FORKEYSHARE: case LCS_FORSHARE: appendStringInfoString(buf, " FOR SHARE"); break; case LCS_FORNOKEYUPDATE: case LCS_FORUPDATE: appendStringInfoString(buf, " FOR UPDATE"); break; } /* Add the relation alias if we are here for a join relation */ if (bms_membership(rel->relids) == BMS_MULTIPLE && rc->strength != LCS_NONE) appendStringInfo(buf, " OF %s%d", REL_ALIAS_PREFIX, relid); } } } } /* * Deparse conditions from the provided list and append them to buf. * * The conditions in the list are assumed to be ANDed. This function is used to * deparse WHERE clauses, JOIN .. ON clauses and HAVING clauses. * * Depending on the caller, the list elements might be either RestrictInfos * or bare clauses. */ static void appendConditions(List *exprs, deparse_expr_cxt *context) { int nestlevel; ListCell *lc; bool is_first = true; StringInfo buf = context->buf; /* Make sure any constants in the exprs are printed portably */ nestlevel = set_transmission_modes(); foreach(lc, exprs) { Expr *expr = (Expr *) lfirst(lc); /* Extract clause from RestrictInfo, if required */ if (IsA(expr, RestrictInfo)) expr = ((RestrictInfo *) expr)->clause; /* Connect expressions with "AND" and parenthesize each condition. */ if (!is_first) appendStringInfoString(buf, " AND "); appendStringInfoChar(buf, '('); deparseExpr(expr, context); appendStringInfoChar(buf, ')'); is_first = false; } reset_transmission_modes(nestlevel); } /* Output join name for given join type */ const char * get_jointype_name(JoinType jointype) { switch (jointype) { case JOIN_INNER: return "INNER"; case JOIN_LEFT: return "LEFT"; case JOIN_RIGHT: return "RIGHT"; case JOIN_FULL: return "FULL"; default: /* Shouldn't come here, but protect from buggy code. */ elog(ERROR, "unsupported join type %d", jointype); } /* Keep compiler happy */ return NULL; } /* * Deparse given targetlist and append it to context->buf. * * tlist is list of TargetEntry's which in turn contain Var nodes. * * retrieved_attrs is the list of continuously increasing integers starting * from 1. It has same number of entries as tlist. * * This is used for both SELECT and RETURNING targetlists; the is_returning * parameter is true only for a RETURNING targetlist. */ static void deparseExplicitTargetList(List *tlist, bool is_returning, List **retrieved_attrs, deparse_expr_cxt *context) { ListCell *lc; StringInfo buf = context->buf; int i = 0; *retrieved_attrs = NIL; foreach(lc, tlist) { TargetEntry *tle = lfirst_node(TargetEntry, lc); if (i > 0) appendStringInfoString(buf, ", "); else if (is_returning) appendStringInfoString(buf, " RETURNING "); deparseExpr((Expr *) tle->expr, context); *retrieved_attrs = lappend_int(*retrieved_attrs, i + 1); i++; } if (i == 0 && !is_returning) appendStringInfoString(buf, "NULL"); } /* * Emit expressions specified in the given relation's reltarget. * * This is used for deparsing the given relation as a subquery. */ static void deparseSubqueryTargetList(deparse_expr_cxt *context) { StringInfo buf = context->buf; RelOptInfo *foreignrel = context->foreignrel; bool first; ListCell *lc; /* Should only be called in these cases. */ Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel)); first = true; foreach(lc, foreignrel->reltarget->exprs) { Node *node = (Node *) lfirst(lc); if (!first) appendStringInfoString(buf, ", "); first = false; deparseExpr((Expr *) node, context); } /* Don't generate bad syntax if no expressions */ if (first) appendStringInfoString(buf, "NULL"); } /* * Construct FROM clause for given relation * * The function constructs ... JOIN ... ON ... for join relation. For a base * relation it just returns schema-qualified tablename, with the appropriate * alias if so requested. * * 'ignore_rel' is either zero or the RT index of a target relation. In the * latter case the function constructs FROM clause of UPDATE or USING clause * of DELETE; it deparses the join relation as if the relation never contained * the target relation, and creates a List of conditions to be deparsed into * the top-level WHERE clause, which is returned to *ignore_conds. */ static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel, bool use_alias, Index ignore_rel, List **ignore_conds, List **params_list) { PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private; if (IS_JOIN_REL(foreignrel)) { StringInfoData join_sql_o; StringInfoData join_sql_i; RelOptInfo *outerrel = fpinfo->outerrel; RelOptInfo *innerrel = fpinfo->innerrel; bool outerrel_is_target = false; bool innerrel_is_target = false; if (ignore_rel > 0 && bms_is_member(ignore_rel, foreignrel->relids)) { /* * If this is an inner join, add joinclauses to *ignore_conds and * set it to empty so that those can be deparsed into the WHERE * clause. Note that since the target relation can never be * within the nullable side of an outer join, those could safely * be pulled up into the WHERE clause (see foreign_join_ok()). * Note also that since the target relation is only inner-joined * to any other relation in the query, all conditions in the join * tree mentioning the target relation could be deparsed into the * WHERE clause by doing this recursively. */ if (fpinfo->jointype == JOIN_INNER) { *ignore_conds = list_concat(*ignore_conds, fpinfo->joinclauses); fpinfo->joinclauses = NIL; } /* * Check if either of the input relations is the target relation. */ if (outerrel->relid == ignore_rel) outerrel_is_target = true; else if (innerrel->relid == ignore_rel) innerrel_is_target = true; } /* Deparse outer relation if not the target relation. */ if (!outerrel_is_target) { initStringInfo(&join_sql_o); deparseRangeTblRef(&join_sql_o, root, outerrel, fpinfo->make_outerrel_subquery, ignore_rel, ignore_conds, params_list); /* * If inner relation is the target relation, skip deparsing it. * Note that since the join of the target relation with any other * relation in the query is an inner join and can never be within * the nullable side of an outer join, the join could be * interchanged with higher-level joins (cf. identity 1 on outer * join reordering shown in src/backend/optimizer/README), which * means it's safe to skip the target-relation deparsing here. */ if (innerrel_is_target) { Assert(fpinfo->jointype == JOIN_INNER); Assert(fpinfo->joinclauses == NIL); appendBinaryStringInfo(buf, join_sql_o.data, join_sql_o.len); return; } } /* Deparse inner relation if not the target relation. */ if (!innerrel_is_target) { initStringInfo(&join_sql_i); deparseRangeTblRef(&join_sql_i, root, innerrel, fpinfo->make_innerrel_subquery, ignore_rel, ignore_conds, params_list); /* * If outer relation is the target relation, skip deparsing it. * See the above note about safety. */ if (outerrel_is_target) { Assert(fpinfo->jointype == JOIN_INNER); Assert(fpinfo->joinclauses == NIL); appendBinaryStringInfo(buf, join_sql_i.data, join_sql_i.len); return; } } /* Neither of the relations is the target relation. */ Assert(!outerrel_is_target && !innerrel_is_target); /* * For a join relation FROM clause entry is deparsed as * * ((outer relation) (inner relation) ON (joinclauses)) */ appendStringInfo(buf, "(%s %s JOIN %s ON ", join_sql_o.data, get_jointype_name(fpinfo->jointype), join_sql_i.data); /* Append join clause; (TRUE) if no join clause */ if (fpinfo->joinclauses) { deparse_expr_cxt context; context.buf = buf; context.foreignrel = foreignrel; context.scanrel = foreignrel; context.root = root; context.params_list = params_list; appendStringInfoChar(buf, '('); appendConditions(fpinfo->joinclauses, &context); appendStringInfoChar(buf, ')'); } else appendStringInfoString(buf, "(TRUE)"); /* End the FROM clause entry. */ appendStringInfoChar(buf, ')'); } else { RangeTblEntry *rte = planner_rt_fetch(foreignrel->relid, root); /* * Core code already has some lock on each rel being planned, so we * can use NoLock here. */ Relation rel = table_open(rte->relid, NoLock); deparseRelation(buf, rel); /* * Add a unique alias to avoid any conflict in relation names due to * pulled up subqueries in the query being built for a pushed down * join. */ if (use_alias) appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, foreignrel->relid); table_close(rel, NoLock); } } /* * Append FROM clause entry for the given relation into buf. */ static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel, bool make_subquery, Index ignore_rel, List **ignore_conds, List **params_list) { PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private; /* Should only be called in these cases. */ Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel)); Assert(fpinfo->local_conds == NIL); /* If make_subquery is true, deparse the relation as a subquery. */ if (make_subquery) { List *retrieved_attrs; int ncols; /* * The given relation shouldn't contain the target relation, because * this should only happen for input relations for a full join, and * such relations can never contain an UPDATE/DELETE target. */ Assert(ignore_rel == 0 || !bms_is_member(ignore_rel, foreignrel->relids)); /* Deparse the subquery representing the relation. */ appendStringInfoChar(buf, '('); deparseSelectStmtForRel(buf, root, foreignrel, NIL, fpinfo->remote_conds, NIL, false, false, true, &retrieved_attrs, params_list); appendStringInfoChar(buf, ')'); /* Append the relation alias. */ appendStringInfo(buf, " %s%d", SUBQUERY_REL_ALIAS_PREFIX, fpinfo->relation_index); /* * Append the column aliases if needed. Note that the subquery emits * expressions specified in the relation's reltarget (see * deparseSubqueryTargetList). */ ncols = list_length(foreignrel->reltarget->exprs); if (ncols > 0) { int i; appendStringInfoChar(buf, '('); for (i = 1; i <= ncols; i++) { if (i > 1) appendStringInfoString(buf, ", "); appendStringInfo(buf, "%s%d", SUBQUERY_COL_ALIAS_PREFIX, i); } appendStringInfoChar(buf, ')'); } } else deparseFromExprForRel(buf, root, foreignrel, true, ignore_rel, ignore_conds, params_list); } /* * deparse remote INSERT statement * * The statement text is appended to buf, and we also create an integer List * of the columns being retrieved by WITH CHECK OPTION or RETURNING (if any), * which is returned to *retrieved_attrs. * * This also stores end position of the VALUES clause, so that we can rebuild * an INSERT for a batch of rows later. */ void deparseInsertSql(StringInfo buf, RangeTblEntry *rte, Index rtindex, Relation rel, List *targetAttrs, bool doNothing, List *withCheckOptionList, List *returningList, List **retrieved_attrs, int *values_end_len) { TupleDesc tupdesc = RelationGetDescr(rel); AttrNumber pindex; bool first; ListCell *lc; appendStringInfoString(buf, "INSERT INTO "); deparseRelation(buf, rel); if (targetAttrs) { appendStringInfoChar(buf, '('); first = true; foreach(lc, targetAttrs) { int attnum = lfirst_int(lc); if (!first) appendStringInfoString(buf, ", "); first = false; deparseColumnRef(buf, rtindex, attnum, rte, false); } appendStringInfoString(buf, ") VALUES ("); pindex = 1; first = true; foreach(lc, targetAttrs) { int attnum = lfirst_int(lc); Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1); if (!first) appendStringInfoString(buf, ", "); first = false; if (attr->attgenerated) appendStringInfoString(buf, "DEFAULT"); else { appendStringInfo(buf, "$%d", pindex); pindex++; } } appendStringInfoChar(buf, ')'); } else appendStringInfoString(buf, " DEFAULT VALUES"); *values_end_len = buf->len; if (doNothing) appendStringInfoString(buf, " ON CONFLICT DO NOTHING"); deparseReturningList(buf, rte, rtindex, rel, rel->trigdesc && rel->trigdesc->trig_insert_after_row, withCheckOptionList, returningList, retrieved_attrs); } /* * rebuild remote INSERT statement * * Provided a number of rows in a batch, builds INSERT statement with the * right number of parameters. */ void rebuildInsertSql(StringInfo buf, Relation rel, char *orig_query, List *target_attrs, int values_end_len, int num_params, int num_rows) { TupleDesc tupdesc = RelationGetDescr(rel); int i; int pindex; bool first; ListCell *lc; /* Make sure the values_end_len is sensible */ Assert((values_end_len > 0) && (values_end_len <= strlen(orig_query))); /* Copy up to the end of the first record from the original query */ appendBinaryStringInfo(buf, orig_query, values_end_len); /* * Add records to VALUES clause (we already have parameters for the first * row, so start at the right offset). */ pindex = num_params + 1; for (i = 0; i < num_rows; i++) { appendStringInfoString(buf, ", ("); first = true; foreach(lc, target_attrs) { int attnum = lfirst_int(lc); Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1); if (!first) appendStringInfoString(buf, ", "); first = false; if (attr->attgenerated) appendStringInfoString(buf, "DEFAULT"); else { appendStringInfo(buf, "$%d", pindex); pindex++; } } appendStringInfoChar(buf, ')'); } /* Copy stuff after VALUES clause from the original query */ appendStringInfoString(buf, orig_query + values_end_len); } /* * deparse remote UPDATE statement * * The statement text is appended to buf, and we also create an integer List * of the columns being retrieved by WITH CHECK OPTION or RETURNING (if any), * which is returned to *retrieved_attrs. */ void deparseUpdateSql(StringInfo buf, RangeTblEntry *rte, Index rtindex, Relation rel, List *targetAttrs, List *withCheckOptionList, List *returningList, List **retrieved_attrs) { TupleDesc tupdesc = RelationGetDescr(rel); AttrNumber pindex; bool first; ListCell *lc; appendStringInfoString(buf, "UPDATE "); deparseRelation(buf, rel); appendStringInfoString(buf, " SET "); pindex = 2; /* ctid is always the first param */ first = true; foreach(lc, targetAttrs) { int attnum = lfirst_int(lc); Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1); if (!first) appendStringInfoString(buf, ", "); first = false; deparseColumnRef(buf, rtindex, attnum, rte, false); if (attr->attgenerated) appendStringInfoString(buf, " = DEFAULT"); else { appendStringInfo(buf, " = $%d", pindex); pindex++; } } appendStringInfoString(buf, " WHERE ctid = $1"); deparseReturningList(buf, rte, rtindex, rel, rel->trigdesc && rel->trigdesc->trig_update_after_row, withCheckOptionList, returningList, retrieved_attrs); } /* * deparse remote UPDATE statement * * 'buf' is the output buffer to append the statement to * 'rtindex' is the RT index of the associated target relation * 'rel' is the relation descriptor for the target relation * 'foreignrel' is the RelOptInfo for the target relation or the join relation * containing all base relations in the query * 'targetlist' is the tlist of the underlying foreign-scan plan node * (note that this only contains new-value expressions and junk attrs) * 'targetAttrs' is the target columns of the UPDATE * 'remote_conds' is the qual clauses that must be evaluated remotely * '*params_list' is an output list of exprs that will become remote Params * 'returningList' is the RETURNING targetlist * '*retrieved_attrs' is an output list of integers of columns being retrieved * by RETURNING (if any) */ void deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root, Index rtindex, Relation rel, RelOptInfo *foreignrel, List *targetlist, List *targetAttrs, List *remote_conds, List **params_list, List *returningList, List **retrieved_attrs) { deparse_expr_cxt context; int nestlevel; bool first; RangeTblEntry *rte = planner_rt_fetch(rtindex, root); ListCell *lc, *lc2; /* Set up context struct for recursion */ context.root = root; context.foreignrel = foreignrel; context.scanrel = foreignrel; context.buf = buf; context.params_list = params_list; appendStringInfoString(buf, "UPDATE "); deparseRelation(buf, rel); if (foreignrel->reloptkind == RELOPT_JOINREL) appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, rtindex); appendStringInfoString(buf, " SET "); /* Make sure any constants in the exprs are printed portably */ nestlevel = set_transmission_modes(); first = true; forboth(lc, targetlist, lc2, targetAttrs) { TargetEntry *tle = lfirst_node(TargetEntry, lc); int attnum = lfirst_int(lc2); /* update's new-value expressions shouldn't be resjunk */ Assert(!tle->resjunk); if (!first) appendStringInfoString(buf, ", "); first = false; deparseColumnRef(buf, rtindex, attnum, rte, false); appendStringInfoString(buf, " = "); deparseExpr((Expr *) tle->expr, &context); } reset_transmission_modes(nestlevel); if (foreignrel->reloptkind == RELOPT_JOINREL) { List *ignore_conds = NIL; appendStringInfoString(buf, " FROM "); deparseFromExprForRel(buf, root, foreignrel, true, rtindex, &ignore_conds, params_list); remote_conds = list_concat(remote_conds, ignore_conds); } if (remote_conds) { appendStringInfoString(buf, " WHERE "); appendConditions(remote_conds, &context); } if (foreignrel->reloptkind == RELOPT_JOINREL) deparseExplicitTargetList(returningList, true, retrieved_attrs, &context); else deparseReturningList(buf, rte, rtindex, rel, false, NIL, returningList, retrieved_attrs); } /* * deparse remote DELETE statement * * The statement text is appended to buf, and we also create an integer List * of the columns being retrieved by RETURNING (if any), which is returned * to *retrieved_attrs. */ void deparseDeleteSql(StringInfo buf, RangeTblEntry *rte, Index rtindex, Relation rel, List *returningList, List **retrieved_attrs) { appendStringInfoString(buf, "DELETE FROM "); deparseRelation(buf, rel); appendStringInfoString(buf, " WHERE ctid = $1"); deparseReturningList(buf, rte, rtindex, rel, rel->trigdesc && rel->trigdesc->trig_delete_after_row, NIL, returningList, retrieved_attrs); } /* * deparse remote DELETE statement * * 'buf' is the output buffer to append the statement to * 'rtindex' is the RT index of the associated target relation * 'rel' is the relation descriptor for the target relation * 'foreignrel' is the RelOptInfo for the target relation or the join relation * containing all base relations in the query * 'remote_conds' is the qual clauses that must be evaluated remotely * '*params_list' is an output list of exprs that will become remote Params * 'returningList' is the RETURNING targetlist * '*retrieved_attrs' is an output list of integers of columns being retrieved * by RETURNING (if any) */ void deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root, Index rtindex, Relation rel, RelOptInfo *foreignrel, List *remote_conds, List **params_list, List *returningList, List **retrieved_attrs) { deparse_expr_cxt context; /* Set up context struct for recursion */ context.root = root; context.foreignrel = foreignrel; context.scanrel = foreignrel; context.buf = buf; context.params_list = params_list; appendStringInfoString(buf, "DELETE FROM "); deparseRelation(buf, rel); if (foreignrel->reloptkind == RELOPT_JOINREL) appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, rtindex); if (foreignrel->reloptkind == RELOPT_JOINREL) { List *ignore_conds = NIL; appendStringInfoString(buf, " USING "); deparseFromExprForRel(buf, root, foreignrel, true, rtindex, &ignore_conds, params_list); remote_conds = list_concat(remote_conds, ignore_conds); } if (remote_conds) { appendStringInfoString(buf, " WHERE "); appendConditions(remote_conds, &context); } if (foreignrel->reloptkind == RELOPT_JOINREL) deparseExplicitTargetList(returningList, true, retrieved_attrs, &context); else deparseReturningList(buf, planner_rt_fetch(rtindex, root), rtindex, rel, false, NIL, returningList, retrieved_attrs); } /* * Add a RETURNING clause, if needed, to an INSERT/UPDATE/DELETE. */ static void deparseReturningList(StringInfo buf, RangeTblEntry *rte, Index rtindex, Relation rel, bool trig_after_row, List *withCheckOptionList, List *returningList, List **retrieved_attrs) { Bitmapset *attrs_used = NULL; if (trig_after_row) { /* whole-row reference acquires all non-system columns */ attrs_used = bms_make_singleton(0 - FirstLowInvalidHeapAttributeNumber); } if (withCheckOptionList != NIL) { /* * We need the attrs, non-system and system, mentioned in the local * query's WITH CHECK OPTION list. * * Note: we do this to ensure that WCO constraints will be evaluated * on the data actually inserted/updated on the remote side, which * might differ from the data supplied by the core code, for example * as a result of remote triggers. */ pull_varattnos((Node *) withCheckOptionList, rtindex, &attrs_used); } if (returningList != NIL) { /* * We need the attrs, non-system and system, mentioned in the local * query's RETURNING list. */ pull_varattnos((Node *) returningList, rtindex, &attrs_used); } if (attrs_used != NULL) deparseTargetList(buf, rte, rtindex, rel, true, attrs_used, false, retrieved_attrs); else *retrieved_attrs = NIL; } /* * Construct SELECT statement to acquire size in blocks of given relation. * * Note: we use local definition of block size, not remote definition. * This is perhaps debatable. * * Note: pg_relation_size() exists in 8.1 and later. */ void deparseAnalyzeSizeSql(StringInfo buf, Relation rel) { StringInfoData relname; /* We'll need the remote relation name as a literal. */ initStringInfo(&relname); deparseRelation(&relname, rel); appendStringInfoString(buf, "SELECT pg_catalog.pg_relation_size("); deparseStringLiteral(buf, relname.data); appendStringInfo(buf, "::pg_catalog.regclass) / %d", BLCKSZ); } /* * Construct SELECT statement to acquire the number of rows and the relkind of * a relation. * * Note: we just return the remote server's reltuples value, which might * be off a good deal, but it doesn't seem worth working harder. See * comments in postgresAcquireSampleRowsFunc. */ void deparseAnalyzeInfoSql(StringInfo buf, Relation rel) { StringInfoData relname; /* We'll need the remote relation name as a literal. */ initStringInfo(&relname); deparseRelation(&relname, rel); appendStringInfoString(buf, "SELECT reltuples, relkind FROM pg_catalog.pg_class WHERE oid = "); deparseStringLiteral(buf, relname.data); appendStringInfoString(buf, "::pg_catalog.regclass"); } /* * Construct SELECT statement to acquire sample rows of given relation. * * SELECT command is appended to buf, and list of columns retrieved * is returned to *retrieved_attrs. * * We only support sampling methods we can decide based on server version. * Allowing custom TSM modules (like tsm_system_rows) might be useful, but it * would require detecting which extensions are installed, to allow automatic * fall-back. Moreover, the methods may use different parameters like number * of rows (and not sampling rate). So we leave this for future improvements. * * Using random() to sample rows on the remote server has the advantage that * this works on all PostgreSQL versions (unlike TABLESAMPLE), and that it * does the sampling on the remote side (without transferring everything and * then discarding most rows). * * The disadvantage is that we still have to read all rows and evaluate the * random(), while TABLESAMPLE (at least with the "system" method) may skip. * It's not that different from the "bernoulli" method, though. * * We could also do "ORDER BY random() LIMIT x", which would always pick * the expected number of rows, but it requires sorting so it may be much * more expensive (particularly on large tables, which is what the * remote sampling is meant to improve). */ void deparseAnalyzeSql(StringInfo buf, Relation rel, PgFdwSamplingMethod sample_method, double sample_frac, List **retrieved_attrs) { Oid relid = RelationGetRelid(rel); TupleDesc tupdesc = RelationGetDescr(rel); int i; char *colname; List *options; ListCell *lc; bool first = true; *retrieved_attrs = NIL; appendStringInfoString(buf, "SELECT "); for (i = 0; i < tupdesc->natts; i++) { /* Ignore dropped columns. */ if (TupleDescAttr(tupdesc, i)->attisdropped) continue; if (!first) appendStringInfoString(buf, ", "); first = false; /* Use attribute name or column_name option. */ colname = NameStr(TupleDescAttr(tupdesc, i)->attname); options = GetForeignColumnOptions(relid, i + 1); foreach(lc, options) { DefElem *def = (DefElem *) lfirst(lc); if (strcmp(def->defname, "column_name") == 0) { colname = defGetString(def); break; } } appendStringInfoString(buf, quote_identifier(colname)); *retrieved_attrs = lappend_int(*retrieved_attrs, i + 1); } /* Don't generate bad syntax for zero-column relation. */ if (first) appendStringInfoString(buf, "NULL"); /* * Construct FROM clause, and perhaps WHERE clause too, depending on the * selected sampling method. */ appendStringInfoString(buf, " FROM "); deparseRelation(buf, rel); switch (sample_method) { case ANALYZE_SAMPLE_OFF: /* nothing to do here */ break; case ANALYZE_SAMPLE_RANDOM: appendStringInfo(buf, " WHERE pg_catalog.random() < %f", sample_frac); break; case ANALYZE_SAMPLE_SYSTEM: appendStringInfo(buf, " TABLESAMPLE SYSTEM(%f)", (100.0 * sample_frac)); break; case ANALYZE_SAMPLE_BERNOULLI: appendStringInfo(buf, " TABLESAMPLE BERNOULLI(%f)", (100.0 * sample_frac)); break; case ANALYZE_SAMPLE_AUTO: /* should have been resolved into actual method */ elog(ERROR, "unexpected sampling method"); break; } } /* * Construct a simple "TRUNCATE rel" statement */ void deparseTruncateSql(StringInfo buf, List *rels, DropBehavior behavior, bool restart_seqs) { ListCell *cell; appendStringInfoString(buf, "TRUNCATE "); foreach(cell, rels) { Relation rel = lfirst(cell); if (cell != list_head(rels)) appendStringInfoString(buf, ", "); deparseRelation(buf, rel); } appendStringInfo(buf, " %s IDENTITY", restart_seqs ? "RESTART" : "CONTINUE"); if (behavior == DROP_RESTRICT) appendStringInfoString(buf, " RESTRICT"); else if (behavior == DROP_CASCADE) appendStringInfoString(buf, " CASCADE"); } /* * Construct name to use for given column, and emit it into buf. * If it has a column_name FDW option, use that instead of attribute name. * * If qualify_col is true, qualify column name with the alias of relation. */ static void deparseColumnRef(StringInfo buf, int varno, int varattno, RangeTblEntry *rte, bool qualify_col) { /* We support fetching the remote side's CTID and OID. */ if (varattno == SelfItemPointerAttributeNumber) { if (qualify_col) ADD_REL_QUALIFIER(buf, varno); appendStringInfoString(buf, "ctid"); } else if (varattno < 0) { /* * All other system attributes are fetched as 0, except for table OID, * which is fetched as the local table OID. However, we must be * careful; the table could be beneath an outer join, in which case it * must go to NULL whenever the rest of the row does. */ Oid fetchval = 0; if (varattno == TableOidAttributeNumber) fetchval = rte->relid; if (qualify_col) { appendStringInfoString(buf, "CASE WHEN ("); ADD_REL_QUALIFIER(buf, varno); appendStringInfo(buf, "*)::text IS NOT NULL THEN %u END", fetchval); } else appendStringInfo(buf, "%u", fetchval); } else if (varattno == 0) { /* Whole row reference */ Relation rel; Bitmapset *attrs_used; /* Required only to be passed down to deparseTargetList(). */ List *retrieved_attrs; /* * The lock on the relation will be held by upper callers, so it's * fine to open it with no lock here. */ rel = table_open(rte->relid, NoLock); /* * The local name of the foreign table can not be recognized by the * foreign server and the table it references on foreign server might * have different column ordering or different columns than those * declared locally. Hence we have to deparse whole-row reference as * ROW(columns referenced locally). Construct this by deparsing a * "whole row" attribute. */ attrs_used = bms_add_member(NULL, 0 - FirstLowInvalidHeapAttributeNumber); /* * In case the whole-row reference is under an outer join then it has * to go NULL whenever the rest of the row goes NULL. Deparsing a join * query would always involve multiple relations, thus qualify_col * would be true. */ if (qualify_col) { appendStringInfoString(buf, "CASE WHEN ("); ADD_REL_QUALIFIER(buf, varno); appendStringInfoString(buf, "*)::text IS NOT NULL THEN "); } appendStringInfoString(buf, "ROW("); deparseTargetList(buf, rte, varno, rel, false, attrs_used, qualify_col, &retrieved_attrs); appendStringInfoChar(buf, ')'); /* Complete the CASE WHEN statement started above. */ if (qualify_col) appendStringInfoString(buf, " END"); table_close(rel, NoLock); bms_free(attrs_used); } else { char *colname = NULL; List *options; ListCell *lc; /* varno must not be any of OUTER_VAR, INNER_VAR and INDEX_VAR. */ Assert(!IS_SPECIAL_VARNO(varno)); /* * If it's a column of a foreign table, and it has the column_name FDW * option, use that value. */ options = GetForeignColumnOptions(rte->relid, varattno); foreach(lc, options) { DefElem *def = (DefElem *) lfirst(lc); if (strcmp(def->defname, "column_name") == 0) { colname = defGetString(def); break; } } /* * If it's a column of a regular table or it doesn't have column_name * FDW option, use attribute name. */ if (colname == NULL) colname = get_attname(rte->relid, varattno, false); if (qualify_col) ADD_REL_QUALIFIER(buf, varno); appendStringInfoString(buf, quote_identifier(colname)); } } /* * Append remote name of specified foreign table to buf. * Use value of table_name FDW option (if any) instead of relation's name. * Similarly, schema_name FDW option overrides schema name. */ static void deparseRelation(StringInfo buf, Relation rel) { ForeignTable *table; const char *nspname = NULL; const char *relname = NULL; ListCell *lc; /* obtain additional catalog information. */ table = GetForeignTable(RelationGetRelid(rel)); /* * Use value of FDW options if any, instead of the name of object itself. */ foreach(lc, table->options) { DefElem *def = (DefElem *) lfirst(lc); if (strcmp(def->defname, "schema_name") == 0) nspname = defGetString(def); else if (strcmp(def->defname, "table_name") == 0) relname = defGetString(def); } /* * Note: we could skip printing the schema name if it's pg_catalog, but * that doesn't seem worth the trouble. */ if (nspname == NULL) nspname = get_namespace_name(RelationGetNamespace(rel)); if (relname == NULL) relname = RelationGetRelationName(rel); appendStringInfo(buf, "%s.%s", quote_identifier(nspname), quote_identifier(relname)); } /* * Append a SQL string literal representing "val" to buf. */ void deparseStringLiteral(StringInfo buf, const char *val) { const char *valptr; /* * Rather than making assumptions about the remote server's value of * standard_conforming_strings, always use E'foo' syntax if there are any * backslashes. This will fail on remote servers before 8.1, but those * are long out of support. */ if (strchr(val, '\\') != NULL) appendStringInfoChar(buf, ESCAPE_STRING_SYNTAX); appendStringInfoChar(buf, '\''); for (valptr = val; *valptr; valptr++) { char ch = *valptr; if (SQL_STR_DOUBLE(ch, true)) appendStringInfoChar(buf, ch); appendStringInfoChar(buf, ch); } appendStringInfoChar(buf, '\''); } /* * Deparse given expression into context->buf. * * This function must support all the same node types that foreign_expr_walker * accepts. * * Note: unlike ruleutils.c, we just use a simple hard-wired parenthesization * scheme: anything more complex than a Var, Const, function call or cast * should be self-parenthesized. */ static void deparseExpr(Expr *node, deparse_expr_cxt *context) { if (node == NULL) return; switch (nodeTag(node)) { case T_Var: deparseVar((Var *) node, context); break; case T_Const: deparseConst((Const *) node, context, 0); break; case T_Param: deparseParam((Param *) node, context); break; case T_SubscriptingRef: deparseSubscriptingRef((SubscriptingRef *) node, context); break; case T_FuncExpr: deparseFuncExpr((FuncExpr *) node, context); break; case T_OpExpr: deparseOpExpr((OpExpr *) node, context); break; case T_DistinctExpr: deparseDistinctExpr((DistinctExpr *) node, context); break; case T_ScalarArrayOpExpr: deparseScalarArrayOpExpr((ScalarArrayOpExpr *) node, context); break; case T_RelabelType: deparseRelabelType((RelabelType *) node, context); break; case T_BoolExpr: deparseBoolExpr((BoolExpr *) node, context); break; case T_NullTest: deparseNullTest((NullTest *) node, context); break; case T_CaseExpr: deparseCaseExpr((CaseExpr *) node, context); break; case T_ArrayExpr: deparseArrayExpr((ArrayExpr *) node, context); break; case T_Aggref: deparseAggref((Aggref *) node, context); break; default: elog(ERROR, "unsupported expression type for deparse: %d", (int) nodeTag(node)); break; } } /* * Deparse given Var node into context->buf. * * If the Var belongs to the foreign relation, just print its remote name. * Otherwise, it's effectively a Param (and will in fact be a Param at * run time). Handle it the same way we handle plain Params --- see * deparseParam for comments. */ static void deparseVar(Var *node, deparse_expr_cxt *context) { Relids relids = context->scanrel->relids; int relno; int colno; /* Qualify columns when multiple relations are involved. */ bool qualify_col = (bms_membership(relids) == BMS_MULTIPLE); /* * If the Var belongs to the foreign relation that is deparsed as a * subquery, use the relation and column alias to the Var provided by the * subquery, instead of the remote name. */ if (is_subquery_var(node, context->scanrel, &relno, &colno)) { appendStringInfo(context->buf, "%s%d.%s%d", SUBQUERY_REL_ALIAS_PREFIX, relno, SUBQUERY_COL_ALIAS_PREFIX, colno); return; } if (bms_is_member(node->varno, relids) && node->varlevelsup == 0) deparseColumnRef(context->buf, node->varno, node->varattno, planner_rt_fetch(node->varno, context->root), qualify_col); else { /* Treat like a Param */ if (context->params_list) { int pindex = 0; ListCell *lc; /* find its index in params_list */ foreach(lc, *context->params_list) { pindex++; if (equal(node, (Node *) lfirst(lc))) break; } if (lc == NULL) { /* not in list, so add it */ pindex++; *context->params_list = lappend(*context->params_list, node); } printRemoteParam(pindex, node->vartype, node->vartypmod, context); } else { printRemotePlaceholder(node->vartype, node->vartypmod, context); } } } /* * Deparse given constant value into context->buf. * * This function has to be kept in sync with ruleutils.c's get_const_expr. * * As in that function, showtype can be -1 to never show "::typename" * decoration, +1 to always show it, or 0 to show it only if the constant * wouldn't be assumed to be the right type by default. * * In addition, this code allows showtype to be -2 to indicate that we should * not show "::typename" decoration if the constant is printed as an untyped * literal or NULL (while in other cases, behaving as for showtype == 0). */ static void deparseConst(Const *node, deparse_expr_cxt *context, int showtype) { StringInfo buf = context->buf; Oid typoutput; bool typIsVarlena; char *extval; bool isfloat = false; bool isstring = false; bool needlabel; if (node->constisnull) { appendStringInfoString(buf, "NULL"); if (showtype >= 0) appendStringInfo(buf, "::%s", deparse_type_name(node->consttype, node->consttypmod)); return; } getTypeOutputInfo(node->consttype, &typoutput, &typIsVarlena); extval = OidOutputFunctionCall(typoutput, node->constvalue); switch (node->consttype) { case INT2OID: case INT4OID: case INT8OID: case OIDOID: case FLOAT4OID: case FLOAT8OID: case NUMERICOID: { /* * No need to quote unless it's a special value such as 'NaN'. * See comments in get_const_expr(). */ if (strspn(extval, "0123456789+-eE.") == strlen(extval)) { if (extval[0] == '+' || extval[0] == '-') appendStringInfo(buf, "(%s)", extval); else appendStringInfoString(buf, extval); if (strcspn(extval, "eE.") != strlen(extval)) isfloat = true; /* it looks like a float */ } else appendStringInfo(buf, "'%s'", extval); } break; case BITOID: case VARBITOID: appendStringInfo(buf, "B'%s'", extval); break; case BOOLOID: if (strcmp(extval, "t") == 0) appendStringInfoString(buf, "true"); else appendStringInfoString(buf, "false"); break; default: deparseStringLiteral(buf, extval); isstring = true; break; } pfree(extval); if (showtype == -1) return; /* never print type label */ /* * For showtype == 0, append ::typename unless the constant will be * implicitly typed as the right type when it is read in. * * XXX this code has to be kept in sync with the behavior of the parser, * especially make_const. */ switch (node->consttype) { case BOOLOID: case INT4OID: case UNKNOWNOID: needlabel = false; break; case NUMERICOID: needlabel = !isfloat || (node->consttypmod >= 0); break; default: if (showtype == -2) { /* label unless we printed it as an untyped string */ needlabel = !isstring; } else needlabel = true; break; } if (needlabel || showtype > 0) appendStringInfo(buf, "::%s", deparse_type_name(node->consttype, node->consttypmod)); } /* * Deparse given Param node. * * If we're generating the query "for real", add the Param to * context->params_list if it's not already present, and then use its index * in that list as the remote parameter number. During EXPLAIN, there's * no need to identify a parameter number. */ static void deparseParam(Param *node, deparse_expr_cxt *context) { if (context->params_list) { int pindex = 0; ListCell *lc; /* find its index in params_list */ foreach(lc, *context->params_list) { pindex++; if (equal(node, (Node *) lfirst(lc))) break; } if (lc == NULL) { /* not in list, so add it */ pindex++; *context->params_list = lappend(*context->params_list, node); } printRemoteParam(pindex, node->paramtype, node->paramtypmod, context); } else { printRemotePlaceholder(node->paramtype, node->paramtypmod, context); } } /* * Deparse a container subscript expression. */ static void deparseSubscriptingRef(SubscriptingRef *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; ListCell *lowlist_item; ListCell *uplist_item; /* Always parenthesize the expression. */ appendStringInfoChar(buf, '('); /* * Deparse referenced array expression first. If that expression includes * a cast, we have to parenthesize to prevent the array subscript from * being taken as typename decoration. We can avoid that in the typical * case of subscripting a Var, but otherwise do it. */ if (IsA(node->refexpr, Var)) deparseExpr(node->refexpr, context); else { appendStringInfoChar(buf, '('); deparseExpr(node->refexpr, context); appendStringInfoChar(buf, ')'); } /* Deparse subscript expressions. */ lowlist_item = list_head(node->reflowerindexpr); /* could be NULL */ foreach(uplist_item, node->refupperindexpr) { appendStringInfoChar(buf, '['); if (lowlist_item) { deparseExpr(lfirst(lowlist_item), context); appendStringInfoChar(buf, ':'); lowlist_item = lnext(node->reflowerindexpr, lowlist_item); } deparseExpr(lfirst(uplist_item), context); appendStringInfoChar(buf, ']'); } appendStringInfoChar(buf, ')'); } /* * Deparse a function call. */ static void deparseFuncExpr(FuncExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; bool use_variadic; bool first; ListCell *arg; /* * If the function call came from an implicit coercion, then just show the * first argument. */ if (node->funcformat == COERCE_IMPLICIT_CAST) { deparseExpr((Expr *) linitial(node->args), context); return; } /* * If the function call came from a cast, then show the first argument * plus an explicit cast operation. */ if (node->funcformat == COERCE_EXPLICIT_CAST) { Oid rettype = node->funcresulttype; int32 coercedTypmod; /* Get the typmod if this is a length-coercion function */ (void) exprIsLengthCoercion((Node *) node, &coercedTypmod); deparseExpr((Expr *) linitial(node->args), context); appendStringInfo(buf, "::%s", deparse_type_name(rettype, coercedTypmod)); return; } /* Check if need to print VARIADIC (cf. ruleutils.c) */ use_variadic = node->funcvariadic; /* * Normal function: display as proname(args). */ appendFunctionName(node->funcid, context); appendStringInfoChar(buf, '('); /* ... and all the arguments */ first = true; foreach(arg, node->args) { if (!first) appendStringInfoString(buf, ", "); if (use_variadic && lnext(node->args, arg) == NULL) appendStringInfoString(buf, "VARIADIC "); deparseExpr((Expr *) lfirst(arg), context); first = false; } appendStringInfoChar(buf, ')'); } /* * Deparse given operator expression. To avoid problems around * priority of operations, we always parenthesize the arguments. */ static void deparseOpExpr(OpExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; HeapTuple tuple; Form_pg_operator form; Expr *right; bool canSuppressRightConstCast = false; char oprkind; /* Retrieve information about the operator from system catalog. */ tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno)); if (!HeapTupleIsValid(tuple)) elog(ERROR, "cache lookup failed for operator %u", node->opno); form = (Form_pg_operator) GETSTRUCT(tuple); oprkind = form->oprkind; /* Sanity check. */ Assert((oprkind == 'l' && list_length(node->args) == 1) || (oprkind == 'b' && list_length(node->args) == 2)); right = llast(node->args); /* Always parenthesize the expression. */ appendStringInfoChar(buf, '('); /* Deparse left operand, if any. */ if (oprkind == 'b') { Expr *left = linitial(node->args); Oid leftType = exprType((Node *) left); Oid rightType = exprType((Node *) right); bool canSuppressLeftConstCast = false; /* * When considering a binary operator, if one operand is a Const that * can be printed as a bare string literal or NULL (i.e., it will look * like type UNKNOWN to the remote parser), the Const normally * receives an explicit cast to the operator's input type. However, * in Const-to-Var comparisons where both operands are of the same * type, we prefer to suppress the explicit cast, leaving the Const's * type resolution up to the remote parser. The remote's resolution * heuristic will assume that an unknown input type being compared to * a known input type is of that known type as well. * * This hack allows some cases to succeed where a remote column is * declared with a different type in the local (foreign) table. By * emitting "foreigncol = 'foo'" not "foreigncol = 'foo'::text" or the * like, we allow the remote parser to pick an "=" operator that's * compatible with whatever type the remote column really is, such as * an enum. * * We allow cast suppression to happen only when the other operand is * a plain foreign Var. Although the remote's unknown-type heuristic * would apply to other cases just as well, we would be taking a * bigger risk that the inferred type is something unexpected. With * this restriction, if anything goes wrong it's the user's fault for * not declaring the local column with the same type as the remote * column. */ if (leftType == rightType) { if (IsA(left, Const)) canSuppressLeftConstCast = isPlainForeignVar(right, context); else if (IsA(right, Const)) canSuppressRightConstCast = isPlainForeignVar(left, context); } if (canSuppressLeftConstCast) deparseConst((Const *) left, context, -2); else deparseExpr(left, context); appendStringInfoChar(buf, ' '); } /* Deparse operator name. */ deparseOperatorName(buf, form); /* Deparse right operand. */ appendStringInfoChar(buf, ' '); if (canSuppressRightConstCast) deparseConst((Const *) right, context, -2); else deparseExpr(right, context); appendStringInfoChar(buf, ')'); ReleaseSysCache(tuple); } /* * Will "node" deparse as a plain foreign Var? */ static bool isPlainForeignVar(Expr *node, deparse_expr_cxt *context) { /* * We allow the foreign Var to have an implicit RelabelType, mainly so * that this'll work with varchar columns. Note that deparseRelabelType * will not print such a cast, so we're not breaking the restriction that * the expression print as a plain Var. We won't risk it for an implicit * cast that requires a function, nor for non-implicit RelabelType; such * cases seem too likely to involve semantics changes compared to what * would happen on the remote side. */ if (IsA(node, RelabelType) && ((RelabelType *) node)->relabelformat == COERCE_IMPLICIT_CAST) node = ((RelabelType *) node)->arg; if (IsA(node, Var)) { /* * The Var must be one that'll deparse as a foreign column reference * (cf. deparseVar). */ Var *var = (Var *) node; Relids relids = context->scanrel->relids; if (bms_is_member(var->varno, relids) && var->varlevelsup == 0) return true; } return false; } /* * Print the name of an operator. */ static void deparseOperatorName(StringInfo buf, Form_pg_operator opform) { char *opname; /* opname is not a SQL identifier, so we should not quote it. */ opname = NameStr(opform->oprname); /* Print schema name only if it's not pg_catalog */ if (opform->oprnamespace != PG_CATALOG_NAMESPACE) { const char *opnspname; opnspname = get_namespace_name(opform->oprnamespace); /* Print fully qualified operator name. */ appendStringInfo(buf, "OPERATOR(%s.%s)", quote_identifier(opnspname), opname); } else { /* Just print operator name. */ appendStringInfoString(buf, opname); } } /* * Deparse IS DISTINCT FROM. */ static void deparseDistinctExpr(DistinctExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; Assert(list_length(node->args) == 2); appendStringInfoChar(buf, '('); deparseExpr(linitial(node->args), context); appendStringInfoString(buf, " IS DISTINCT FROM "); deparseExpr(lsecond(node->args), context); appendStringInfoChar(buf, ')'); } /* * Deparse given ScalarArrayOpExpr expression. To avoid problems * around priority of operations, we always parenthesize the arguments. */ static void deparseScalarArrayOpExpr(ScalarArrayOpExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; HeapTuple tuple; Form_pg_operator form; Expr *arg1; Expr *arg2; /* Retrieve information about the operator from system catalog. */ tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno)); if (!HeapTupleIsValid(tuple)) elog(ERROR, "cache lookup failed for operator %u", node->opno); form = (Form_pg_operator) GETSTRUCT(tuple); /* Sanity check. */ Assert(list_length(node->args) == 2); /* Always parenthesize the expression. */ appendStringInfoChar(buf, '('); /* Deparse left operand. */ arg1 = linitial(node->args); deparseExpr(arg1, context); appendStringInfoChar(buf, ' '); /* Deparse operator name plus decoration. */ deparseOperatorName(buf, form); appendStringInfo(buf, " %s (", node->useOr ? "ANY" : "ALL"); /* Deparse right operand. */ arg2 = lsecond(node->args); deparseExpr(arg2, context); appendStringInfoChar(buf, ')'); /* Always parenthesize the expression. */ appendStringInfoChar(buf, ')'); ReleaseSysCache(tuple); } /* * Deparse a RelabelType (binary-compatible cast) node. */ static void deparseRelabelType(RelabelType *node, deparse_expr_cxt *context) { deparseExpr(node->arg, context); if (node->relabelformat != COERCE_IMPLICIT_CAST) appendStringInfo(context->buf, "::%s", deparse_type_name(node->resulttype, node->resulttypmod)); } /* * Deparse a BoolExpr node. */ static void deparseBoolExpr(BoolExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; const char *op = NULL; /* keep compiler quiet */ bool first; ListCell *lc; switch (node->boolop) { case AND_EXPR: op = "AND"; break; case OR_EXPR: op = "OR"; break; case NOT_EXPR: appendStringInfoString(buf, "(NOT "); deparseExpr(linitial(node->args), context); appendStringInfoChar(buf, ')'); return; } appendStringInfoChar(buf, '('); first = true; foreach(lc, node->args) { if (!first) appendStringInfo(buf, " %s ", op); deparseExpr((Expr *) lfirst(lc), context); first = false; } appendStringInfoChar(buf, ')'); } /* * Deparse IS [NOT] NULL expression. */ static void deparseNullTest(NullTest *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; appendStringInfoChar(buf, '('); deparseExpr(node->arg, context); /* * For scalar inputs, we prefer to print as IS [NOT] NULL, which is * shorter and traditional. If it's a rowtype input but we're applying a * scalar test, must print IS [NOT] DISTINCT FROM NULL to be semantically * correct. */ if (node->argisrow || !type_is_rowtype(exprType((Node *) node->arg))) { if (node->nulltesttype == IS_NULL) appendStringInfoString(buf, " IS NULL)"); else appendStringInfoString(buf, " IS NOT NULL)"); } else { if (node->nulltesttype == IS_NULL) appendStringInfoString(buf, " IS NOT DISTINCT FROM NULL)"); else appendStringInfoString(buf, " IS DISTINCT FROM NULL)"); } } /* * Deparse CASE expression */ static void deparseCaseExpr(CaseExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; ListCell *lc; appendStringInfoString(buf, "(CASE"); /* If this is a CASE arg WHEN then emit the arg expression */ if (node->arg != NULL) { appendStringInfoChar(buf, ' '); deparseExpr(node->arg, context); } /* Add each condition/result of the CASE clause */ foreach(lc, node->args) { CaseWhen *whenclause = (CaseWhen *) lfirst(lc); /* WHEN */ appendStringInfoString(buf, " WHEN "); if (node->arg == NULL) /* CASE WHEN */ deparseExpr(whenclause->expr, context); else /* CASE arg WHEN */ { /* Ignore the CaseTestExpr and equality operator. */ deparseExpr(lsecond(castNode(OpExpr, whenclause->expr)->args), context); } /* THEN */ appendStringInfoString(buf, " THEN "); deparseExpr(whenclause->result, context); } /* add ELSE if present */ if (node->defresult != NULL) { appendStringInfoString(buf, " ELSE "); deparseExpr(node->defresult, context); } /* append END */ appendStringInfoString(buf, " END)"); } /* * Deparse ARRAY[...] construct. */ static void deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; bool first = true; ListCell *lc; appendStringInfoString(buf, "ARRAY["); foreach(lc, node->elements) { if (!first) appendStringInfoString(buf, ", "); deparseExpr(lfirst(lc), context); first = false; } appendStringInfoChar(buf, ']'); /* If the array is empty, we need an explicit cast to the array type. */ if (node->elements == NIL) appendStringInfo(buf, "::%s", deparse_type_name(node->array_typeid, -1)); } /* * Deparse an Aggref node. */ static void deparseAggref(Aggref *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; bool use_variadic; /* Only basic, non-split aggregation accepted. */ Assert(node->aggsplit == AGGSPLIT_SIMPLE); /* Check if need to print VARIADIC (cf. ruleutils.c) */ use_variadic = node->aggvariadic; /* Find aggregate name from aggfnoid which is a pg_proc entry */ appendFunctionName(node->aggfnoid, context); appendStringInfoChar(buf, '('); /* Add DISTINCT */ appendStringInfoString(buf, (node->aggdistinct != NIL) ? "DISTINCT " : ""); if (AGGKIND_IS_ORDERED_SET(node->aggkind)) { /* Add WITHIN GROUP (ORDER BY ..) */ ListCell *arg; bool first = true; Assert(!node->aggvariadic); Assert(node->aggorder != NIL); foreach(arg, node->aggdirectargs) { if (!first) appendStringInfoString(buf, ", "); first = false; deparseExpr((Expr *) lfirst(arg), context); } appendStringInfoString(buf, ") WITHIN GROUP (ORDER BY "); appendAggOrderBy(node->aggorder, node->args, context); } else { /* aggstar can be set only in zero-argument aggregates */ if (node->aggstar) appendStringInfoChar(buf, '*'); else { ListCell *arg; bool first = true; /* Add all the arguments */ foreach(arg, node->args) { TargetEntry *tle = (TargetEntry *) lfirst(arg); Node *n = (Node *) tle->expr; if (tle->resjunk) continue; if (!first) appendStringInfoString(buf, ", "); first = false; /* Add VARIADIC */ if (use_variadic && lnext(node->args, arg) == NULL) appendStringInfoString(buf, "VARIADIC "); deparseExpr((Expr *) n, context); } } /* Add ORDER BY */ if (node->aggorder != NIL) { appendStringInfoString(buf, " ORDER BY "); appendAggOrderBy(node->aggorder, node->args, context); } } /* Add FILTER (WHERE ..) */ if (node->aggfilter != NULL) { appendStringInfoString(buf, ") FILTER (WHERE "); deparseExpr((Expr *) node->aggfilter, context); } appendStringInfoChar(buf, ')'); } /* * Append ORDER BY within aggregate function. */ static void appendAggOrderBy(List *orderList, List *targetList, deparse_expr_cxt *context) { StringInfo buf = context->buf; ListCell *lc; bool first = true; foreach(lc, orderList) { SortGroupClause *srt = (SortGroupClause *) lfirst(lc); Node *sortexpr; if (!first) appendStringInfoString(buf, ", "); first = false; /* Deparse the sort expression proper. */ sortexpr = deparseSortGroupClause(srt->tleSortGroupRef, targetList, false, context); /* Add decoration as needed. */ appendOrderBySuffix(srt->sortop, exprType(sortexpr), srt->nulls_first, context); } } /* * Append the ASC, DESC, USING and NULLS FIRST / NULLS LAST parts * of an ORDER BY clause. */ static void appendOrderBySuffix(Oid sortop, Oid sortcoltype, bool nulls_first, deparse_expr_cxt *context) { StringInfo buf = context->buf; TypeCacheEntry *typentry; /* See whether operator is default < or > for sort expr's datatype. */ typentry = lookup_type_cache(sortcoltype, TYPECACHE_LT_OPR | TYPECACHE_GT_OPR); if (sortop == typentry->lt_opr) appendStringInfoString(buf, " ASC"); else if (sortop == typentry->gt_opr) appendStringInfoString(buf, " DESC"); else { HeapTuple opertup; Form_pg_operator operform; appendStringInfoString(buf, " USING "); /* Append operator name. */ opertup = SearchSysCache1(OPEROID, ObjectIdGetDatum(sortop)); if (!HeapTupleIsValid(opertup)) elog(ERROR, "cache lookup failed for operator %u", sortop); operform = (Form_pg_operator) GETSTRUCT(opertup); deparseOperatorName(buf, operform); ReleaseSysCache(opertup); } if (nulls_first) appendStringInfoString(buf, " NULLS FIRST"); else appendStringInfoString(buf, " NULLS LAST"); } /* * Print the representation of a parameter to be sent to the remote side. * * Note: we always label the Param's type explicitly rather than relying on * transmitting a numeric type OID in PQexecParams(). This allows us to * avoid assuming that types have the same OIDs on the remote side as they * do locally --- they need only have the same names. */ static void printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod, deparse_expr_cxt *context) { StringInfo buf = context->buf; char *ptypename = deparse_type_name(paramtype, paramtypmod); appendStringInfo(buf, "$%d::%s", paramindex, ptypename); } /* * Print the representation of a placeholder for a parameter that will be * sent to the remote side at execution time. * * This is used when we're just trying to EXPLAIN the remote query. * We don't have the actual value of the runtime parameter yet, and we don't * want the remote planner to generate a plan that depends on such a value * anyway. Thus, we can't do something simple like "$1::paramtype". * Instead, we emit "((SELECT null::paramtype)::paramtype)". * In all extant versions of Postgres, the planner will see that as an unknown * constant value, which is what we want. This might need adjustment if we * ever make the planner flatten scalar subqueries. Note: the reason for the * apparently useless outer cast is to ensure that the representation as a * whole will be parsed as an a_expr and not a select_with_parens; the latter * would do the wrong thing in the context "x = ANY(...)". */ static void printRemotePlaceholder(Oid paramtype, int32 paramtypmod, deparse_expr_cxt *context) { StringInfo buf = context->buf; char *ptypename = deparse_type_name(paramtype, paramtypmod); appendStringInfo(buf, "((SELECT null::%s)::%s)", ptypename, ptypename); } /* * Deparse GROUP BY clause. */ static void appendGroupByClause(List *tlist, deparse_expr_cxt *context) { StringInfo buf = context->buf; Query *query = context->root->parse; ListCell *lc; bool first = true; /* Nothing to be done, if there's no GROUP BY clause in the query. */ if (!query->groupClause) return; appendStringInfoString(buf, " GROUP BY "); /* * Queries with grouping sets are not pushed down, so we don't expect * grouping sets here. */ Assert(!query->groupingSets); /* * We intentionally print query->groupClause not processed_groupClause, * leaving it to the remote planner to get rid of any redundant GROUP BY * items again. This is necessary in case processed_groupClause reduced * to empty, and in any case the redundancy situation on the remote might * be different than what we think here. */ foreach(lc, query->groupClause) { SortGroupClause *grp = (SortGroupClause *) lfirst(lc); if (!first) appendStringInfoString(buf, ", "); first = false; deparseSortGroupClause(grp->tleSortGroupRef, tlist, true, context); } } /* * Deparse ORDER BY clause defined by the given pathkeys. * * The clause should use Vars from context->scanrel if !has_final_sort, * or from context->foreignrel's targetlist if has_final_sort. * * We find a suitable pathkey expression (some earlier step * should have verified that there is one) and deparse it. */ static void appendOrderByClause(List *pathkeys, bool has_final_sort, deparse_expr_cxt *context) { ListCell *lcell; int nestlevel; const char *delim = " "; StringInfo buf = context->buf; /* Make sure any constants in the exprs are printed portably */ nestlevel = set_transmission_modes(); appendStringInfoString(buf, " ORDER BY"); foreach(lcell, pathkeys) { PathKey *pathkey = lfirst(lcell); EquivalenceMember *em; Expr *em_expr; Oid oprid; if (has_final_sort) { /* * By construction, context->foreignrel is the input relation to * the final sort. */ em = find_em_for_rel_target(context->root, pathkey->pk_eclass, context->foreignrel); } else em = find_em_for_rel(context->root, pathkey->pk_eclass, context->scanrel); /* * We don't expect any error here; it would mean that shippability * wasn't verified earlier. For the same reason, we don't recheck * shippability of the sort operator. */ if (em == NULL) elog(ERROR, "could not find pathkey item to sort"); em_expr = em->em_expr; /* * Lookup the operator corresponding to the strategy in the opclass. * The datatype used by the opfamily is not necessarily the same as * the expression type (for array types for example). */ oprid = get_opfamily_member(pathkey->pk_opfamily, em->em_datatype, em->em_datatype, pathkey->pk_strategy); if (!OidIsValid(oprid)) elog(ERROR, "missing operator %d(%u,%u) in opfamily %u", pathkey->pk_strategy, em->em_datatype, em->em_datatype, pathkey->pk_opfamily); appendStringInfoString(buf, delim); deparseExpr(em_expr, context); /* * Here we need to use the expression's actual type to discover * whether the desired operator will be the default or not. */ appendOrderBySuffix(oprid, exprType((Node *) em_expr), pathkey->pk_nulls_first, context); delim = ", "; } reset_transmission_modes(nestlevel); } /* * Deparse LIMIT/OFFSET clause. */ static void appendLimitClause(deparse_expr_cxt *context) { PlannerInfo *root = context->root; StringInfo buf = context->buf; int nestlevel; /* Make sure any constants in the exprs are printed portably */ nestlevel = set_transmission_modes(); if (root->parse->limitCount) { appendStringInfoString(buf, " LIMIT "); deparseExpr((Expr *) root->parse->limitCount, context); } if (root->parse->limitOffset) { appendStringInfoString(buf, " OFFSET "); deparseExpr((Expr *) root->parse->limitOffset, context); } reset_transmission_modes(nestlevel); } /* * appendFunctionName * Deparses function name from given function oid. */ static void appendFunctionName(Oid funcid, deparse_expr_cxt *context) { StringInfo buf = context->buf; HeapTuple proctup; Form_pg_proc procform; const char *proname; proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid)); if (!HeapTupleIsValid(proctup)) elog(ERROR, "cache lookup failed for function %u", funcid); procform = (Form_pg_proc) GETSTRUCT(proctup); /* Print schema name only if it's not pg_catalog */ if (procform->pronamespace != PG_CATALOG_NAMESPACE) { const char *schemaname; schemaname = get_namespace_name(procform->pronamespace); appendStringInfo(buf, "%s.", quote_identifier(schemaname)); } /* Always print the function name */ proname = NameStr(procform->proname); appendStringInfoString(buf, quote_identifier(proname)); ReleaseSysCache(proctup); } /* * Appends a sort or group clause. * * Like get_rule_sortgroupclause(), returns the expression tree, so caller * need not find it again. */ static Node * deparseSortGroupClause(Index ref, List *tlist, bool force_colno, deparse_expr_cxt *context) { StringInfo buf = context->buf; TargetEntry *tle; Expr *expr; tle = get_sortgroupref_tle(ref, tlist); expr = tle->expr; if (force_colno) { /* Use column-number form when requested by caller. */ Assert(!tle->resjunk); appendStringInfo(buf, "%d", tle->resno); } else if (expr && IsA(expr, Const)) { /* * Force a typecast here so that we don't emit something like "GROUP * BY 2", which will be misconstrued as a column position rather than * a constant. */ deparseConst((Const *) expr, context, 1); } else if (!expr || IsA(expr, Var)) deparseExpr(expr, context); else { /* Always parenthesize the expression. */ appendStringInfoChar(buf, '('); deparseExpr(expr, context); appendStringInfoChar(buf, ')'); } return (Node *) expr; } /* * Returns true if given Var is deparsed as a subquery output column, in * which case, *relno and *colno are set to the IDs for the relation and * column alias to the Var provided by the subquery. */ static bool is_subquery_var(Var *node, RelOptInfo *foreignrel, int *relno, int *colno) { PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private; RelOptInfo *outerrel = fpinfo->outerrel; RelOptInfo *innerrel = fpinfo->innerrel; /* Should only be called in these cases. */ Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel)); /* * If the given relation isn't a join relation, it doesn't have any lower * subqueries, so the Var isn't a subquery output column. */ if (!IS_JOIN_REL(foreignrel)) return false; /* * If the Var doesn't belong to any lower subqueries, it isn't a subquery * output column. */ if (!bms_is_member(node->varno, fpinfo->lower_subquery_rels)) return false; if (bms_is_member(node->varno, outerrel->relids)) { /* * If outer relation is deparsed as a subquery, the Var is an output * column of the subquery; get the IDs for the relation/column alias. */ if (fpinfo->make_outerrel_subquery) { get_relation_column_alias_ids(node, outerrel, relno, colno); return true; } /* Otherwise, recurse into the outer relation. */ return is_subquery_var(node, outerrel, relno, colno); } else { Assert(bms_is_member(node->varno, innerrel->relids)); /* * If inner relation is deparsed as a subquery, the Var is an output * column of the subquery; get the IDs for the relation/column alias. */ if (fpinfo->make_innerrel_subquery) { get_relation_column_alias_ids(node, innerrel, relno, colno); return true; } /* Otherwise, recurse into the inner relation. */ return is_subquery_var(node, innerrel, relno, colno); } } /* * Get the IDs for the relation and column alias to given Var belonging to * given relation, which are returned into *relno and *colno. */ static void get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel, int *relno, int *colno) { PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private; int i; ListCell *lc; /* Get the relation alias ID */ *relno = fpinfo->relation_index; /* Get the column alias ID */ i = 1; foreach(lc, foreignrel->reltarget->exprs) { Var *tlvar = (Var *) lfirst(lc); /* * Match reltarget entries only on varno/varattno. Ideally there * would be some cross-check on varnullingrels, but it's unclear what * to do exactly; we don't have enough context to know what that value * should be. */ if (IsA(tlvar, Var) && tlvar->varno == node->varno && tlvar->varattno == node->varattno) { *colno = i; return; } i++; } /* Shouldn't get here */ elog(ERROR, "unexpected expression in subquery output"); }