postgresql/contrib/postgres_fdw/deparse.c
Tom Lane 21734d2fb8 Support writable foreign tables.
This patch adds the core-system infrastructure needed to support updates
on foreign tables, and extends contrib/postgres_fdw to allow updates
against remote Postgres servers.  There's still a great deal of room for
improvement in optimization of remote updates, but at least there's basic
functionality there now.

KaiGai Kohei, reviewed by Alexander Korotkov and Laurenz Albe, and rather
heavily revised by Tom Lane.
2013-03-10 14:16:02 -04:00

1380 lines
35 KiB
C

/*-------------------------------------------------------------------------
*
* 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.
*
* Portions Copyright (c) 2012-2013, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/postgres_fdw/deparse.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "postgres_fdw.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "access/transam.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/var.h"
#include "parser/parsetree.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/syscache.h"
/*
* Context for foreign_expr_walker's search of an expression tree.
*/
typedef struct foreign_expr_cxt
{
/* Input values */
PlannerInfo *root;
RelOptInfo *foreignrel;
/* Result values */
List *param_numbers; /* Param IDs of PARAM_EXTERN Params */
} foreign_expr_cxt;
/*
* Functions to determine whether an expression can be evaluated safely on
* remote server.
*/
static bool is_foreign_expr(PlannerInfo *root, RelOptInfo *baserel,
Expr *expr, List **param_numbers);
static bool foreign_expr_walker(Node *node, foreign_expr_cxt *context);
static bool is_builtin(Oid procid);
/*
* Functions to construct string representation of a node tree.
*/
static void deparseTargetList(StringInfo buf,
PlannerInfo *root,
Index rtindex,
Relation rel,
Bitmapset *attrs_used);
static void deparseReturningList(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
List *returningList);
static void deparseColumnRef(StringInfo buf, int varno, int varattno,
PlannerInfo *root);
static void deparseRelation(StringInfo buf, Oid relid);
static void deparseStringLiteral(StringInfo buf, const char *val);
static void deparseExpr(StringInfo buf, Expr *expr, PlannerInfo *root);
static void deparseVar(StringInfo buf, Var *node, PlannerInfo *root);
static void deparseConst(StringInfo buf, Const *node, PlannerInfo *root);
static void deparseParam(StringInfo buf, Param *node, PlannerInfo *root);
static void deparseArrayRef(StringInfo buf, ArrayRef *node, PlannerInfo *root);
static void deparseFuncExpr(StringInfo buf, FuncExpr *node, PlannerInfo *root);
static void deparseOpExpr(StringInfo buf, OpExpr *node, PlannerInfo *root);
static void deparseOperatorName(StringInfo buf, Form_pg_operator opform);
static void deparseDistinctExpr(StringInfo buf, DistinctExpr *node,
PlannerInfo *root);
static void deparseScalarArrayOpExpr(StringInfo buf, ScalarArrayOpExpr *node,
PlannerInfo *root);
static void deparseRelabelType(StringInfo buf, RelabelType *node,
PlannerInfo *root);
static void deparseBoolExpr(StringInfo buf, BoolExpr *node, PlannerInfo *root);
static void deparseNullTest(StringInfo buf, NullTest *node, PlannerInfo *root);
static void deparseArrayExpr(StringInfo buf, ArrayExpr *node,
PlannerInfo *root);
/*
* Examine each restriction clause in baserel's baserestrictinfo list,
* and classify them into three groups, which are returned as three lists:
* - remote_conds contains expressions that can be evaluated remotely,
* and contain no PARAM_EXTERN Params
* - param_conds contains expressions that can be evaluated remotely,
* but contain one or more PARAM_EXTERN Params
* - local_conds contains all expressions that can't be evaluated remotely
*
* In addition, the fourth output parameter param_numbers receives an integer
* list of the param IDs of the PARAM_EXTERN Params used in param_conds.
*
* The reason for segregating param_conds is mainly that it's difficult to
* use such conditions in remote EXPLAIN. We could do it, but unless the
* planner has been given representative values for all the Params, we'd
* have to guess at representative values to use in EXPLAIN EXECUTE.
* So for now we don't include them when doing remote EXPLAIN.
*/
void
classifyConditions(PlannerInfo *root,
RelOptInfo *baserel,
List **remote_conds,
List **param_conds,
List **local_conds,
List **param_numbers)
{
ListCell *lc;
*remote_conds = NIL;
*param_conds = NIL;
*local_conds = NIL;
*param_numbers = NIL;
foreach(lc, baserel->baserestrictinfo)
{
RestrictInfo *ri = (RestrictInfo *) lfirst(lc);
List *cur_param_numbers;
if (is_foreign_expr(root, baserel, ri->clause, &cur_param_numbers))
{
if (cur_param_numbers == NIL)
*remote_conds = lappend(*remote_conds, ri);
else
{
*param_conds = lappend(*param_conds, ri);
/* Use list_concat_unique_int to get rid of duplicates */
*param_numbers = list_concat_unique_int(*param_numbers,
cur_param_numbers);
}
}
else
*local_conds = lappend(*local_conds, ri);
}
}
/*
* Returns true if given expr is safe to evaluate on the foreign server.
*
* If result is true, we also return a list of param IDs of PARAM_EXTERN
* Params appearing in the expr into *param_numbers.
*/
static bool
is_foreign_expr(PlannerInfo *root,
RelOptInfo *baserel,
Expr *expr,
List **param_numbers)
{
foreign_expr_cxt context;
*param_numbers = NIL; /* default result */
/*
* Check that the expression consists of nodes that are safe to execute
* remotely.
*/
context.root = root;
context.foreignrel = baserel;
context.param_numbers = NIL;
if (foreign_expr_walker((Node *) expr, &context))
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, so return list of param IDs too.
*/
*param_numbers = context.param_numbers;
return true;
}
/*
* Return true if expression includes any node that is not safe to execute
* remotely. (We use this convention because expression_tree_walker is
* designed to abort the tree walk as soon as a TRUE result is detected.)
*/
static bool
foreign_expr_walker(Node *node, foreign_expr_cxt *context)
{
bool check_type = true;
if (node == NULL)
return false;
switch (nodeTag(node))
{
case T_Var:
{
/*
* Var can be used if it is in the foreign table (we shouldn't
* really see anything else in baserestrict clauses, but let's
* check anyway).
*/
Var *var = (Var *) node;
if (var->varno != context->foreignrel->relid ||
var->varlevelsup != 0)
return true;
}
break;
case T_Const:
/* OK */
break;
case T_Param:
{
Param *p = (Param *) node;
/*
* Only external parameters can be sent to remote. (XXX This
* needs to be improved, but at the point where this code
* runs, we should only see PARAM_EXTERN Params anyway.)
*/
if (p->paramkind != PARAM_EXTERN)
return true;
/*
* Report IDs of PARAM_EXTERN Params. We don't bother to
* eliminate duplicate list elements here; classifyConditions
* will do that.
*/
context->param_numbers = lappend_int(context->param_numbers,
p->paramid);
}
break;
case T_ArrayRef:
{
ArrayRef *ar = (ArrayRef *) node;;
/* Assignment should not be in restrictions. */
if (ar->refassgnexpr != NULL)
return true;
}
break;
case T_FuncExpr:
{
/*
* If function used by the expression is not built-in, it
* can't be sent to remote because it might have incompatible
* semantics on remote side.
*/
FuncExpr *fe = (FuncExpr *) node;
if (!is_builtin(fe->funcid))
return true;
}
break;
case T_OpExpr:
case T_DistinctExpr: /* struct-equivalent to OpExpr */
{
/*
* Similarly, only built-in operators can be sent to remote.
* (If the operator is, surely its underlying function is
* too.)
*/
OpExpr *oe = (OpExpr *) node;
if (!is_builtin(oe->opno))
return true;
}
break;
case T_ScalarArrayOpExpr:
{
/*
* Again, only built-in operators can be sent to remote.
*/
ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node;
if (!is_builtin(oe->opno))
return true;
}
break;
case T_RelabelType:
case T_BoolExpr:
case T_NullTest:
case T_ArrayExpr:
/* OK */
break;
case T_List:
/*
* We need only fall through to let expression_tree_walker scan
* the list elements --- but don't apply exprType() to the list.
*/
check_type = false;
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 true;
}
/*
* If result type of given expression is not built-in, it can't be sent to
* remote because it might have incompatible semantics on remote side.
*/
if (check_type && !is_builtin(exprType(node)))
return true;
/* Recurse to examine sub-nodes */
return expression_tree_walker(node, foreign_expr_walker, context);
}
/*
* Return true if given object is one of PostgreSQL's built-in objects.
*
* We use FirstBootstrapObjectId as the cutoff, so that we only consider
* objects with hand-assigned OIDs to be "built in", not for instance any
* function or type defined in the information_schema.
*
* Our constraints for dealing with types are tighter than they are for
* functions or operators: we want to accept only types that are in pg_catalog,
* else format_type might incorrectly fail to schema-qualify their names.
* (This could be fixed with some changes to format_type, but for now there's
* no need.) Thus we must exclude information_schema types.
*
* XXX there is a problem with this, which is that the set of built-in
* objects expands over time. Something that is built-in to us might not
* be known to the remote server, if it's of an older version. But keeping
* track of that would be a huge exercise.
*/
static bool
is_builtin(Oid oid)
{
return (oid < FirstBootstrapObjectId);
}
/*
* Construct a simple SELECT statement that retrieves desired columns
* of the specified foreign table, and append it to "buf". The output
* contains just "SELECT ... FROM tablename".
*/
void
deparseSelectSql(StringInfo buf,
PlannerInfo *root,
RelOptInfo *baserel,
Bitmapset *attrs_used)
{
RangeTblEntry *rte = planner_rt_fetch(baserel->relid, root);
Relation rel;
/*
* Core code already has some lock on each rel being planned, so we can
* use NoLock here.
*/
rel = heap_open(rte->relid, NoLock);
/*
* Construct SELECT list
*/
appendStringInfoString(buf, "SELECT ");
deparseTargetList(buf, root, baserel->relid, rel, attrs_used);
/*
* Construct FROM clause
*/
appendStringInfoString(buf, " FROM ");
deparseRelation(buf, RelationGetRelid(rel));
heap_close(rel, NoLock);
}
/*
* Emit a target list that retrieves the columns specified in attrs_used.
* This is used for both SELECT and RETURNING targetlists.
*
* We list attributes in order of the foreign table's columns, but replace
* any attributes that need not be fetched with NULL constants. (We can't
* just omit such attributes, or we'll lose track of which columns are
* which at runtime.) Note however that any dropped columns are ignored.
* Also, if ctid needs to be retrieved, it's added at the end.
*/
static void
deparseTargetList(StringInfo buf,
PlannerInfo *root,
Index rtindex,
Relation rel,
Bitmapset *attrs_used)
{
TupleDesc tupdesc = RelationGetDescr(rel);
bool have_wholerow;
bool first;
int i;
/* 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 = tupdesc->attrs[i - 1];
/* Ignore dropped attributes. */
if (attr->attisdropped)
continue;
if (!first)
appendStringInfoString(buf, ", ");
first = false;
if (have_wholerow ||
bms_is_member(i - FirstLowInvalidHeapAttributeNumber,
attrs_used))
deparseColumnRef(buf, rtindex, i, root);
else
appendStringInfoString(buf, "NULL");
}
/*
* 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, ", ");
first = false;
appendStringInfoString(buf, "ctid");
}
/* Don't generate bad syntax if no undropped columns */
if (first)
appendStringInfoString(buf, "NULL");
}
/*
* Deparse WHERE clauses in given list of RestrictInfos and append them to buf.
*
* If no WHERE clause already exists in the buffer, is_first should be true.
*/
void
appendWhereClause(StringInfo buf,
PlannerInfo *root,
List *exprs,
bool is_first)
{
ListCell *lc;
foreach(lc, exprs)
{
RestrictInfo *ri = (RestrictInfo *) lfirst(lc);
/* Connect expressions with "AND" and parenthesize each condition. */
if (is_first)
appendStringInfoString(buf, " WHERE ");
else
appendStringInfoString(buf, " AND ");
appendStringInfoChar(buf, '(');
deparseExpr(buf, ri->clause, root);
appendStringInfoChar(buf, ')');
is_first = false;
}
}
/*
* deparse remote INSERT statement
*/
void
deparseInsertSql(StringInfo buf, PlannerInfo *root, Index rtindex,
List *targetAttrs, List *returningList)
{
RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
Relation rel = heap_open(rte->relid, NoLock);
TupleDesc tupdesc = RelationGetDescr(rel);
AttrNumber pindex;
bool first;
ListCell *lc;
appendStringInfoString(buf, "INSERT INTO ");
deparseRelation(buf, rte->relid);
appendStringInfoString(buf, "(");
first = true;
foreach(lc, targetAttrs)
{
int attnum = lfirst_int(lc);
Form_pg_attribute attr = tupdesc->attrs[attnum - 1];
Assert(!attr->attisdropped);
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseColumnRef(buf, rtindex, attnum, root);
}
appendStringInfoString(buf, ") VALUES (");
pindex = 1;
first = true;
foreach(lc, targetAttrs)
{
if (!first)
appendStringInfoString(buf, ", ");
first = false;
appendStringInfo(buf, "$%d", pindex);
pindex++;
}
appendStringInfoString(buf, ")");
if (returningList)
deparseReturningList(buf, root, rtindex, rel, returningList);
heap_close(rel, NoLock);
}
/*
* deparse remote UPDATE statement
*/
void
deparseUpdateSql(StringInfo buf, PlannerInfo *root, Index rtindex,
List *targetAttrs, List *returningList)
{
RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
Relation rel = heap_open(rte->relid, NoLock);
TupleDesc tupdesc = RelationGetDescr(rel);
AttrNumber pindex;
bool first;
ListCell *lc;
appendStringInfoString(buf, "UPDATE ");
deparseRelation(buf, rte->relid);
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 = tupdesc->attrs[attnum - 1];
Assert(!attr->attisdropped);
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseColumnRef(buf, rtindex, attnum, root);
appendStringInfo(buf, " = $%d", pindex);
pindex++;
}
appendStringInfoString(buf, " WHERE ctid = $1");
if (returningList)
deparseReturningList(buf, root, rtindex, rel, returningList);
heap_close(rel, NoLock);
}
/*
* deparse remote DELETE statement
*/
void
deparseDeleteSql(StringInfo buf, PlannerInfo *root, Index rtindex,
List *returningList)
{
RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
appendStringInfoString(buf, "DELETE FROM ");
deparseRelation(buf, rte->relid);
appendStringInfoString(buf, " WHERE ctid = $1");
if (returningList)
{
Relation rel = heap_open(rte->relid, NoLock);
deparseReturningList(buf, root, rtindex, rel, returningList);
heap_close(rel, NoLock);
}
}
/*
* deparse RETURNING clause of INSERT/UPDATE/DELETE
*/
static void
deparseReturningList(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
List *returningList)
{
Bitmapset *attrs_used;
/*
* We need the attrs mentioned in the query's RETURNING list.
*/
attrs_used = NULL;
pull_varattnos((Node *) returningList, rtindex,
&attrs_used);
appendStringInfoString(buf, " RETURNING ");
deparseTargetList(buf, root, rtindex, rel, attrs_used);
}
/*
* 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)
{
Oid relid = RelationGetRelid(rel);
StringInfoData relname;
/* We'll need the remote relation name as a literal. */
initStringInfo(&relname);
deparseRelation(&relname, relid);
appendStringInfo(buf, "SELECT pg_catalog.pg_relation_size(");
deparseStringLiteral(buf, relname.data);
appendStringInfo(buf, "::pg_catalog.regclass) / %d", BLCKSZ);
}
/*
* Construct SELECT statement to acquire sample rows of given relation.
*
* Note: command is appended to whatever might be in buf already.
*/
void
deparseAnalyzeSql(StringInfo buf, Relation rel)
{
Oid relid = RelationGetRelid(rel);
TupleDesc tupdesc = RelationGetDescr(rel);
int i;
char *colname;
List *options;
ListCell *lc;
bool first = true;
appendStringInfoString(buf, "SELECT ");
for (i = 0; i < tupdesc->natts; i++)
{
/* Ignore dropped columns. */
if (tupdesc->attrs[i]->attisdropped)
continue;
if (!first)
appendStringInfoString(buf, ", ");
first = false;
/* Use attribute name or column_name option. */
colname = NameStr(tupdesc->attrs[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));
}
/* Don't generate bad syntax for zero-column relation. */
if (first)
appendStringInfoString(buf, "NULL");
/*
* Construct FROM clause
*/
appendStringInfoString(buf, " FROM ");
deparseRelation(buf, relid);
}
/*
* 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.
*/
static void
deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root)
{
RangeTblEntry *rte;
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));
/* Get RangeTblEntry from array in PlannerInfo. */
rte = planner_rt_fetch(varno, root);
/*
* 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_relid_attribute_name(rte->relid, varattno);
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, Oid relid)
{
ForeignTable *table;
const char *nspname = NULL;
const char *relname = NULL;
ListCell *lc;
/* obtain additional catalog information. */
table = GetForeignTable(relid);
/*
* 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(get_rel_namespace(relid));
if (relname == NULL)
relname = get_rel_name(relid);
appendStringInfo(buf, "%s.%s",
quote_identifier(nspname), quote_identifier(relname));
}
/*
* Append a SQL string literal representing "val" to buf.
*/
static 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 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(StringInfo buf, Expr *node, PlannerInfo *root)
{
if (node == NULL)
return;
switch (nodeTag(node))
{
case T_Var:
deparseVar(buf, (Var *) node, root);
break;
case T_Const:
deparseConst(buf, (Const *) node, root);
break;
case T_Param:
deparseParam(buf, (Param *) node, root);
break;
case T_ArrayRef:
deparseArrayRef(buf, (ArrayRef *) node, root);
break;
case T_FuncExpr:
deparseFuncExpr(buf, (FuncExpr *) node, root);
break;
case T_OpExpr:
deparseOpExpr(buf, (OpExpr *) node, root);
break;
case T_DistinctExpr:
deparseDistinctExpr(buf, (DistinctExpr *) node, root);
break;
case T_ScalarArrayOpExpr:
deparseScalarArrayOpExpr(buf, (ScalarArrayOpExpr *) node, root);
break;
case T_RelabelType:
deparseRelabelType(buf, (RelabelType *) node, root);
break;
case T_BoolExpr:
deparseBoolExpr(buf, (BoolExpr *) node, root);
break;
case T_NullTest:
deparseNullTest(buf, (NullTest *) node, root);
break;
case T_ArrayExpr:
deparseArrayExpr(buf, (ArrayExpr *) node, root);
break;
default:
elog(ERROR, "unsupported expression type for deparse: %d",
(int) nodeTag(node));
break;
}
}
/*
* Deparse given Var node into buf.
*/
static void
deparseVar(StringInfo buf, Var *node, PlannerInfo *root)
{
Assert(node->varlevelsup == 0);
deparseColumnRef(buf, node->varno, node->varattno, root);
}
/*
* Deparse given constant value into buf.
*
* This function has to be kept in sync with ruleutils.c's get_const_expr.
*/
static void
deparseConst(StringInfo buf, Const *node, PlannerInfo *root)
{
Oid typoutput;
bool typIsVarlena;
char *extval;
bool isfloat = false;
bool needlabel;
if (node->constisnull)
{
appendStringInfo(buf, "NULL");
appendStringInfo(buf, "::%s",
format_type_with_typemod(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);
break;
}
/*
* 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:
needlabel = true;
break;
}
if (needlabel)
appendStringInfo(buf, "::%s",
format_type_with_typemod(node->consttype,
node->consttypmod));
}
/*
* Deparse given Param node into buf.
*
* We don't need to renumber the parameter ID, because the executor functions
* in postgres_fdw.c preserve the numbering of PARAM_EXTERN Params.
* (This might change soon.)
*
* Note: we 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
deparseParam(StringInfo buf, Param *node, PlannerInfo *root)
{
Assert(node->paramkind == PARAM_EXTERN);
appendStringInfo(buf, "$%d", node->paramid);
appendStringInfo(buf, "::%s",
format_type_with_typemod(node->paramtype,
node->paramtypmod));
}
/*
* Deparse an array subscript expression.
*/
static void
deparseArrayRef(StringInfo buf, ArrayRef *node, PlannerInfo *root)
{
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(buf, node->refexpr, root);
else
{
appendStringInfoChar(buf, '(');
deparseExpr(buf, node->refexpr, root);
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(buf, lfirst(lowlist_item), root);
appendStringInfoChar(buf, ':');
lowlist_item = lnext(lowlist_item);
}
deparseExpr(buf, lfirst(uplist_item), root);
appendStringInfoChar(buf, ']');
}
appendStringInfoChar(buf, ')');
}
/*
* Deparse given node which represents a function call into buf.
*/
static void
deparseFuncExpr(StringInfo buf, FuncExpr *node, PlannerInfo *root)
{
HeapTuple proctup;
Form_pg_proc procform;
const char *proname;
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(buf, (Expr *) linitial(node->args), root);
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(buf, (Expr *) linitial(node->args), root);
appendStringInfo(buf, "::%s",
format_type_with_typemod(rettype, coercedTypmod));
return;
}
/*
* Normal function: display as proname(args).
*/
proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(node->funcid));
if (!HeapTupleIsValid(proctup))
elog(ERROR, "cache lookup failed for function %u", node->funcid);
procform = (Form_pg_proc) GETSTRUCT(proctup);
/* Check if need to print VARIADIC (cf. ruleutils.c) */
if (OidIsValid(procform->provariadic))
{
if (procform->provariadic != ANYOID)
use_variadic = true;
else
use_variadic = node->funcvariadic;
}
else
use_variadic = false;
/* 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));
}
/* Deparse the function name ... */
proname = NameStr(procform->proname);
appendStringInfo(buf, "%s(", quote_identifier(proname));
/* ... and all the arguments */
first = true;
foreach(arg, node->args)
{
if (!first)
appendStringInfoString(buf, ", ");
if (use_variadic && lnext(arg) == NULL)
appendStringInfoString(buf, "VARIADIC ");
deparseExpr(buf, (Expr *) lfirst(arg), root);
first = false;
}
appendStringInfoChar(buf, ')');
ReleaseSysCache(proctup);
}
/*
* Deparse given operator expression into buf. To avoid problems around
* priority of operations, we always parenthesize the arguments.
*/
static void
deparseOpExpr(StringInfo buf, OpExpr *node, PlannerInfo *root)
{
HeapTuple tuple;
Form_pg_operator form;
char oprkind;
ListCell *arg;
/* 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 == 'r' && list_length(node->args) == 1) ||
(oprkind == 'l' && list_length(node->args) == 1) ||
(oprkind == 'b' && list_length(node->args) == 2));
/* Always parenthesize the expression. */
appendStringInfoChar(buf, '(');
/* Deparse left operand. */
if (oprkind == 'r' || oprkind == 'b')
{
arg = list_head(node->args);
deparseExpr(buf, lfirst(arg), root);
appendStringInfoChar(buf, ' ');
}
/* Deparse operator name. */
deparseOperatorName(buf, form);
/* Deparse right operand. */
if (oprkind == 'l' || oprkind == 'b')
{
arg = list_tail(node->args);
appendStringInfoChar(buf, ' ');
deparseExpr(buf, lfirst(arg), root);
}
appendStringInfoChar(buf, ')');
ReleaseSysCache(tuple);
}
/*
* 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. */
appendStringInfo(buf, "%s", opname);
}
}
/*
* Deparse IS DISTINCT FROM.
*/
static void
deparseDistinctExpr(StringInfo buf, DistinctExpr *node, PlannerInfo *root)
{
Assert(list_length(node->args) == 2);
appendStringInfoChar(buf, '(');
deparseExpr(buf, linitial(node->args), root);
appendStringInfoString(buf, " IS DISTINCT FROM ");
deparseExpr(buf, lsecond(node->args), root);
appendStringInfoChar(buf, ')');
}
/*
* Deparse given ScalarArrayOpExpr expression into buf. To avoid problems
* around priority of operations, we always parenthesize the arguments.
*/
static void
deparseScalarArrayOpExpr(StringInfo buf,
ScalarArrayOpExpr *node,
PlannerInfo *root)
{
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(buf, arg1, root);
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(buf, arg2, root);
appendStringInfoChar(buf, ')');
/* Always parenthesize the expression. */
appendStringInfoChar(buf, ')');
ReleaseSysCache(tuple);
}
/*
* Deparse a RelabelType (binary-compatible cast) node.
*/
static void
deparseRelabelType(StringInfo buf, RelabelType *node, PlannerInfo *root)
{
deparseExpr(buf, node->arg, root);
if (node->relabelformat != COERCE_IMPLICIT_CAST)
appendStringInfo(buf, "::%s",
format_type_with_typemod(node->resulttype,
node->resulttypmod));
}
/*
* Deparse a BoolExpr node.
*
* Note: by the time we get here, AND and OR expressions have been flattened
* into N-argument form, so we'd better be prepared to deal with that.
*/
static void
deparseBoolExpr(StringInfo buf, BoolExpr *node, PlannerInfo *root)
{
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(buf, linitial(node->args), root);
appendStringInfoChar(buf, ')');
return;
}
appendStringInfoChar(buf, '(');
first = true;
foreach(lc, node->args)
{
if (!first)
appendStringInfo(buf, " %s ", op);
deparseExpr(buf, (Expr *) lfirst(lc), root);
first = false;
}
appendStringInfoChar(buf, ')');
}
/*
* Deparse IS [NOT] NULL expression.
*/
static void
deparseNullTest(StringInfo buf, NullTest *node, PlannerInfo *root)
{
appendStringInfoChar(buf, '(');
deparseExpr(buf, node->arg, root);
if (node->nulltesttype == IS_NULL)
appendStringInfoString(buf, " IS NULL)");
else
appendStringInfoString(buf, " IS NOT NULL)");
}
/*
* Deparse ARRAY[...] construct.
*/
static void
deparseArrayExpr(StringInfo buf, ArrayExpr *node, PlannerInfo *root)
{
bool first = true;
ListCell *lc;
appendStringInfoString(buf, "ARRAY[");
foreach(lc, node->elements)
{
if (!first)
appendStringInfoString(buf, ", ");
deparseExpr(buf, lfirst(lc), root);
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",
format_type_with_typemod(node->array_typeid, -1));
}