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postgresql/src/backend/optimizer/util/appendinfo.c

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/*-------------------------------------------------------------------------
*
* appendinfo.c
* Routines for mapping between append parent(s) and children
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/optimizer/util/appendinfo.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "access/table.h"
#include "foreign/fdwapi.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/appendinfo.h"
#include "optimizer/pathnode.h"
#include "optimizer/planmain.h"
#include "parser/parsetree.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
typedef struct
{
PlannerInfo *root;
int nappinfos;
AppendRelInfo **appinfos;
} adjust_appendrel_attrs_context;
static void make_inh_translation_list(Relation oldrelation,
Relation newrelation,
Index newvarno,
AppendRelInfo *appinfo);
static Node *adjust_appendrel_attrs_mutator(Node *node,
adjust_appendrel_attrs_context *context);
/*
* make_append_rel_info
* Build an AppendRelInfo for the parent-child pair
*/
AppendRelInfo *
make_append_rel_info(Relation parentrel, Relation childrel,
Index parentRTindex, Index childRTindex)
{
AppendRelInfo *appinfo = makeNode(AppendRelInfo);
appinfo->parent_relid = parentRTindex;
appinfo->child_relid = childRTindex;
appinfo->parent_reltype = parentrel->rd_rel->reltype;
appinfo->child_reltype = childrel->rd_rel->reltype;
make_inh_translation_list(parentrel, childrel, childRTindex, appinfo);
appinfo->parent_reloid = RelationGetRelid(parentrel);
return appinfo;
}
/*
* make_inh_translation_list
* Build the list of translations from parent Vars to child Vars for
* an inheritance child, as well as a reverse-translation array.
*
* The reverse-translation array has an entry for each child relation
* column, which is either the 1-based index of the corresponding parent
* column, or 0 if there's no match (that happens for dropped child columns,
* as well as child columns beyond those of the parent, which are allowed in
* traditional inheritance though not partitioning).
*
* For paranoia's sake, we match type/collation as well as attribute name.
*/
static void
make_inh_translation_list(Relation oldrelation, Relation newrelation,
Index newvarno,
AppendRelInfo *appinfo)
{
List *vars = NIL;
AttrNumber *pcolnos;
TupleDesc old_tupdesc = RelationGetDescr(oldrelation);
TupleDesc new_tupdesc = RelationGetDescr(newrelation);
Oid new_relid = RelationGetRelid(newrelation);
int oldnatts = old_tupdesc->natts;
int newnatts = new_tupdesc->natts;
int old_attno;
int new_attno = 0;
/* Initialize reverse-translation array with all entries zero */
appinfo->num_child_cols = newnatts;
appinfo->parent_colnos = pcolnos =
(AttrNumber *) palloc0(newnatts * sizeof(AttrNumber));
for (old_attno = 0; old_attno < oldnatts; old_attno++)
{
Form_pg_attribute att;
char *attname;
Oid atttypid;
int32 atttypmod;
Oid attcollation;
att = TupleDescAttr(old_tupdesc, old_attno);
if (att->attisdropped)
{
/* Just put NULL into this list entry */
vars = lappend(vars, NULL);
continue;
}
attname = NameStr(att->attname);
atttypid = att->atttypid;
atttypmod = att->atttypmod;
attcollation = att->attcollation;
/*
* When we are generating the "translation list" for the parent table
* of an inheritance set, no need to search for matches.
*/
if (oldrelation == newrelation)
{
vars = lappend(vars, makeVar(newvarno,
(AttrNumber) (old_attno + 1),
atttypid,
atttypmod,
attcollation,
0));
pcolnos[old_attno] = old_attno + 1;
continue;
}
/*
* Otherwise we have to search for the matching column by name.
* There's no guarantee it'll have the same column position, because
* of cases like ALTER TABLE ADD COLUMN and multiple inheritance.
* However, in simple cases, the relative order of columns is mostly
* the same in both relations, so try the column of newrelation that
* follows immediately after the one that we just found, and if that
* fails, let syscache handle it.
*/
if (new_attno >= newnatts ||
(att = TupleDescAttr(new_tupdesc, new_attno))->attisdropped ||
strcmp(attname, NameStr(att->attname)) != 0)
{
HeapTuple newtup;
newtup = SearchSysCacheAttName(new_relid, attname);
if (!HeapTupleIsValid(newtup))
elog(ERROR, "could not find inherited attribute \"%s\" of relation \"%s\"",
attname, RelationGetRelationName(newrelation));
new_attno = ((Form_pg_attribute) GETSTRUCT(newtup))->attnum - 1;
Assert(new_attno >= 0 && new_attno < newnatts);
ReleaseSysCache(newtup);
att = TupleDescAttr(new_tupdesc, new_attno);
}
/* Found it, check type and collation match */
if (atttypid != att->atttypid || atttypmod != att->atttypmod)
elog(ERROR, "attribute \"%s\" of relation \"%s\" does not match parent's type",
attname, RelationGetRelationName(newrelation));
if (attcollation != att->attcollation)
elog(ERROR, "attribute \"%s\" of relation \"%s\" does not match parent's collation",
attname, RelationGetRelationName(newrelation));
vars = lappend(vars, makeVar(newvarno,
(AttrNumber) (new_attno + 1),
atttypid,
atttypmod,
attcollation,
0));
pcolnos[new_attno] = old_attno + 1;
new_attno++;
}
appinfo->translated_vars = vars;
}
/*
* adjust_appendrel_attrs
* Copy the specified query or expression and translate Vars referring to a
* parent rel to refer to the corresponding child rel instead. We also
* update rtindexes appearing outside Vars, such as resultRelation and
* jointree relids.
*
* Note: this is only applied after conversion of sublinks to subplans,
* so we don't need to cope with recursion into sub-queries.
*
* Note: this is not hugely different from what pullup_replace_vars() does;
* maybe we should try to fold the two routines together.
*/
Node *
adjust_appendrel_attrs(PlannerInfo *root, Node *node, int nappinfos,
AppendRelInfo **appinfos)
{
adjust_appendrel_attrs_context context;
context.root = root;
context.nappinfos = nappinfos;
context.appinfos = appinfos;
/* If there's nothing to adjust, don't call this function. */
Assert(nappinfos >= 1 && appinfos != NULL);
/* Should never be translating a Query tree. */
Assert(node == NULL || !IsA(node, Query));
return adjust_appendrel_attrs_mutator(node, &context);
}
static Node *
adjust_appendrel_attrs_mutator(Node *node,
adjust_appendrel_attrs_context *context)
{
AppendRelInfo **appinfos = context->appinfos;
int nappinfos = context->nappinfos;
int cnt;
if (node == NULL)
return NULL;
if (IsA(node, Var))
{
Var *var = (Var *) copyObject(node);
AppendRelInfo *appinfo = NULL;
if (var->varlevelsup != 0)
return (Node *) var; /* no changes needed */
/*
* You might think we need to adjust var->varnullingrels, but that
* shouldn't need any changes. It will contain outer-join relids,
* while the transformation we are making affects only baserels.
* Below, we just propagate var->varnullingrels into the translated
* Var.
*
* If var->varnullingrels isn't empty, and the translation wouldn't be
* a Var, we have to fail. One could imagine wrapping the translated
* expression in a PlaceHolderVar, but that won't work because this is
* typically used after freezing placeholders. Fortunately, the case
* appears unreachable at the moment. We can see nonempty
* var->varnullingrels here, but only in cases involving partitionwise
* joining, and in such cases the translations will always be Vars.
* (Non-Var translations occur only for appendrels made by flattening
* UNION ALL subqueries.) Should we need to make this work in future,
* a possible fix is to mandate that prepjointree.c create PHVs for
* all non-Var outputs of such subqueries, and then we could look up
* the pre-existing PHV here. Or perhaps just wrap the translations
* that way to begin with?
*/
for (cnt = 0; cnt < nappinfos; cnt++)
{
if (var->varno == appinfos[cnt]->parent_relid)
{
appinfo = appinfos[cnt];
break;
}
}
if (appinfo)
{
var->varno = appinfo->child_relid;
/* it's now a generated Var, so drop any syntactic labeling */
var->varnosyn = 0;
var->varattnosyn = 0;
if (var->varattno > 0)
{
Node *newnode;
if (var->varattno > list_length(appinfo->translated_vars))
elog(ERROR, "attribute %d of relation \"%s\" does not exist",
var->varattno, get_rel_name(appinfo->parent_reloid));
newnode = copyObject(list_nth(appinfo->translated_vars,
var->varattno - 1));
if (newnode == NULL)
elog(ERROR, "attribute %d of relation \"%s\" does not exist",
var->varattno, get_rel_name(appinfo->parent_reloid));
if (IsA(newnode, Var))
((Var *) newnode)->varnullingrels = var->varnullingrels;
else if (var->varnullingrels != NULL)
elog(ERROR, "failed to apply nullingrels to a non-Var");
return newnode;
}
else if (var->varattno == 0)
{
/*
* Whole-row Var: if we are dealing with named rowtypes, we
* can use a whole-row Var for the child table plus a coercion
* step to convert the tuple layout to the parent's rowtype.
* Otherwise we have to generate a RowExpr.
*/
if (OidIsValid(appinfo->child_reltype))
{
Assert(var->vartype == appinfo->parent_reltype);
if (appinfo->parent_reltype != appinfo->child_reltype)
{
ConvertRowtypeExpr *r = makeNode(ConvertRowtypeExpr);
r->arg = (Expr *) var;
r->resulttype = appinfo->parent_reltype;
r->convertformat = COERCE_IMPLICIT_CAST;
r->location = -1;
/* Make sure the Var node has the right type ID, too */
var->vartype = appinfo->child_reltype;
return (Node *) r;
}
}
else
{
/*
* Build a RowExpr containing the translated variables.
*
* In practice var->vartype will always be RECORDOID here,
* so we need to come up with some suitable column names.
* We use the parent RTE's column names.
*
* Note: we can't get here for inheritance cases, so there
* is no need to worry that translated_vars might contain
* some dummy NULLs.
*/
RowExpr *rowexpr;
List *fields;
RangeTblEntry *rte;
rte = rt_fetch(appinfo->parent_relid,
context->root->parse->rtable);
fields = copyObject(appinfo->translated_vars);
rowexpr = makeNode(RowExpr);
rowexpr->args = fields;
rowexpr->row_typeid = var->vartype;
rowexpr->row_format = COERCE_IMPLICIT_CAST;
rowexpr->colnames = copyObject(rte->eref->colnames);
rowexpr->location = -1;
if (var->varnullingrels != NULL)
elog(ERROR, "failed to apply nullingrels to a non-Var");
return (Node *) rowexpr;
}
}
/* system attributes don't need any other translation */
}
else if (var->varno == ROWID_VAR)
{
/*
* If it's a ROWID_VAR placeholder, see if we've reached a leaf
* target rel, for which we can translate the Var to a specific
* instantiation. We should never be asked to translate to a set
* of relids containing more than one leaf target rel, so the
* answer will be unique. If we're still considering non-leaf
* inheritance levels, return the ROWID_VAR Var as-is.
*/
Relids leaf_result_relids = context->root->leaf_result_relids;
Index leaf_relid = 0;
for (cnt = 0; cnt < nappinfos; cnt++)
{
if (bms_is_member(appinfos[cnt]->child_relid,
leaf_result_relids))
{
if (leaf_relid)
elog(ERROR, "cannot translate to multiple leaf relids");
leaf_relid = appinfos[cnt]->child_relid;
}
}
if (leaf_relid)
{
RowIdentityVarInfo *ridinfo = (RowIdentityVarInfo *)
list_nth(context->root->row_identity_vars, var->varattno - 1);
if (bms_is_member(leaf_relid, ridinfo->rowidrels))
{
/* Substitute the Var given in the RowIdentityVarInfo */
var = copyObject(ridinfo->rowidvar);
/* ... but use the correct relid */
var->varno = leaf_relid;
/* identity vars shouldn't have nulling rels */
Assert(var->varnullingrels == NULL);
/* varnosyn in the RowIdentityVarInfo is probably wrong */
var->varnosyn = 0;
var->varattnosyn = 0;
}
else
{
/*
* This leaf rel can't return the desired value, so
* substitute a NULL of the correct type.
*/
return (Node *) makeNullConst(var->vartype,
var->vartypmod,
var->varcollid);
}
}
}
return (Node *) var;
}
if (IsA(node, CurrentOfExpr))
{
CurrentOfExpr *cexpr = (CurrentOfExpr *) copyObject(node);
for (cnt = 0; cnt < nappinfos; cnt++)
{
AppendRelInfo *appinfo = appinfos[cnt];
if (cexpr->cvarno == appinfo->parent_relid)
{
cexpr->cvarno = appinfo->child_relid;
break;
}
}
return (Node *) cexpr;
}
if (IsA(node, PlaceHolderVar))
{
/* Copy the PlaceHolderVar node with correct mutation of subnodes */
PlaceHolderVar *phv;
phv = (PlaceHolderVar *) expression_tree_mutator(node,
adjust_appendrel_attrs_mutator,
(void *) context);
/* now fix PlaceHolderVar's relid sets */
if (phv->phlevelsup == 0)
{
phv->phrels = adjust_child_relids(phv->phrels,
nappinfos, appinfos);
/* as above, we needn't touch phnullingrels */
}
return (Node *) phv;
}
/* Shouldn't need to handle planner auxiliary nodes here */
Assert(!IsA(node, SpecialJoinInfo));
Assert(!IsA(node, AppendRelInfo));
Assert(!IsA(node, PlaceHolderInfo));
Assert(!IsA(node, MinMaxAggInfo));
/*
* We have to process RestrictInfo nodes specially. (Note: although
* set_append_rel_pathlist will hide RestrictInfos in the parent's
* baserestrictinfo list from us, it doesn't hide those in joininfo.)
*/
if (IsA(node, RestrictInfo))
{
RestrictInfo *oldinfo = (RestrictInfo *) node;
RestrictInfo *newinfo = makeNode(RestrictInfo);
/* Copy all flat-copiable fields, notably including rinfo_serial */
memcpy(newinfo, oldinfo, sizeof(RestrictInfo));
/* Recursively fix the clause itself */
newinfo->clause = (Expr *)
adjust_appendrel_attrs_mutator((Node *) oldinfo->clause, context);
/* and the modified version, if an OR clause */
newinfo->orclause = (Expr *)
adjust_appendrel_attrs_mutator((Node *) oldinfo->orclause, context);
/* adjust relid sets too */
newinfo->clause_relids = adjust_child_relids(oldinfo->clause_relids,
context->nappinfos,
context->appinfos);
newinfo->required_relids = adjust_child_relids(oldinfo->required_relids,
context->nappinfos,
context->appinfos);
newinfo->outer_relids = adjust_child_relids(oldinfo->outer_relids,
context->nappinfos,
context->appinfos);
newinfo->left_relids = adjust_child_relids(oldinfo->left_relids,
context->nappinfos,
context->appinfos);
newinfo->right_relids = adjust_child_relids(oldinfo->right_relids,
context->nappinfos,
context->appinfos);
/*
* Reset cached derivative fields, since these might need to have
* different values when considering the child relation. Note we
* don't reset left_ec/right_ec: each child variable is implicitly
* equivalent to its parent, so still a member of the same EC if any.
*/
newinfo->eval_cost.startup = -1;
newinfo->norm_selec = -1;
newinfo->outer_selec = -1;
newinfo->left_em = NULL;
newinfo->right_em = NULL;
newinfo->scansel_cache = NIL;
newinfo->left_bucketsize = -1;
newinfo->right_bucketsize = -1;
newinfo->left_mcvfreq = -1;
newinfo->right_mcvfreq = -1;
return (Node *) newinfo;
}
/*
* NOTE: we do not need to recurse into sublinks, because they should
* already have been converted to subplans before we see them.
*/
Assert(!IsA(node, SubLink));
Assert(!IsA(node, Query));
/* We should never see these Query substructures, either. */
Assert(!IsA(node, RangeTblRef));
Assert(!IsA(node, JoinExpr));
return expression_tree_mutator(node, adjust_appendrel_attrs_mutator,
(void *) context);
}
/*
* adjust_appendrel_attrs_multilevel
* Apply Var translations from an appendrel parent down to a child.
*
* Replace Vars in the "node" expression that reference "parentrel" with
* the appropriate Vars for "childrel". childrel can be more than one
* inheritance level removed from parentrel.
*/
Node *
adjust_appendrel_attrs_multilevel(PlannerInfo *root, Node *node,
RelOptInfo *childrel,
RelOptInfo *parentrel)
{
AppendRelInfo **appinfos;
int nappinfos;
/* Recurse if immediate parent is not the top parent. */
if (childrel->parent != parentrel)
{
if (childrel->parent)
node = adjust_appendrel_attrs_multilevel(root, node,
childrel->parent,
parentrel);
else
elog(ERROR, "childrel is not a child of parentrel");
}
/* Now translate for this child. */
appinfos = find_appinfos_by_relids(root, childrel->relids, &nappinfos);
node = adjust_appendrel_attrs(root, node, nappinfos, appinfos);
pfree(appinfos);
return node;
}
/*
* Substitute child relids for parent relids in a Relid set. The array of
* appinfos specifies the substitutions to be performed.
*/
Relids
adjust_child_relids(Relids relids, int nappinfos, AppendRelInfo **appinfos)
{
Bitmapset *result = NULL;
int cnt;
for (cnt = 0; cnt < nappinfos; cnt++)
{
AppendRelInfo *appinfo = appinfos[cnt];
/* Remove parent, add child */
if (bms_is_member(appinfo->parent_relid, relids))
{
/* Make a copy if we are changing the set. */
if (!result)
result = bms_copy(relids);
result = bms_del_member(result, appinfo->parent_relid);
result = bms_add_member(result, appinfo->child_relid);
}
}
/* If we made any changes, return the modified copy. */
if (result)
return result;
/* Otherwise, return the original set without modification. */
return relids;
}
/*
* Substitute child's relids for parent's relids in a Relid set.
* The childrel can be multiple inheritance levels below the parent.
*/
Relids
adjust_child_relids_multilevel(PlannerInfo *root, Relids relids,
RelOptInfo *childrel,
RelOptInfo *parentrel)
{
AppendRelInfo **appinfos;
int nappinfos;
/*
* If the given relids set doesn't contain any of the parent relids, it
* will remain unchanged.
*/
if (!bms_overlap(relids, parentrel->relids))
return relids;
/* Recurse if immediate parent is not the top parent. */
if (childrel->parent != parentrel)
{
if (childrel->parent)
relids = adjust_child_relids_multilevel(root, relids,
childrel->parent,
parentrel);
else
elog(ERROR, "childrel is not a child of parentrel");
}
/* Now translate for this child. */
appinfos = find_appinfos_by_relids(root, childrel->relids, &nappinfos);
relids = adjust_child_relids(relids, nappinfos, appinfos);
pfree(appinfos);
return relids;
}
/*
* adjust_inherited_attnums
* Translate an integer list of attribute numbers from parent to child.
*/
List *
adjust_inherited_attnums(List *attnums, AppendRelInfo *context)
{
List *result = NIL;
ListCell *lc;
/* This should only happen for an inheritance case, not UNION ALL */
Assert(OidIsValid(context->parent_reloid));
/* Look up each attribute in the AppendRelInfo's translated_vars list */
foreach(lc, attnums)
{
AttrNumber parentattno = lfirst_int(lc);
Var *childvar;
/* Look up the translation of this column: it must be a Var */
if (parentattno <= 0 ||
parentattno > list_length(context->translated_vars))
elog(ERROR, "attribute %d of relation \"%s\" does not exist",
parentattno, get_rel_name(context->parent_reloid));
childvar = (Var *) list_nth(context->translated_vars, parentattno - 1);
if (childvar == NULL || !IsA(childvar, Var))
elog(ERROR, "attribute %d of relation \"%s\" does not exist",
parentattno, get_rel_name(context->parent_reloid));
result = lappend_int(result, childvar->varattno);
}
return result;
}
/*
* adjust_inherited_attnums_multilevel
* As above, but traverse multiple inheritance levels as needed.
*/
List *
adjust_inherited_attnums_multilevel(PlannerInfo *root, List *attnums,
Index child_relid, Index top_parent_relid)
{
AppendRelInfo *appinfo = root->append_rel_array[child_relid];
if (!appinfo)
elog(ERROR, "child rel %d not found in append_rel_array", child_relid);
/* Recurse if immediate parent is not the top parent. */
if (appinfo->parent_relid != top_parent_relid)
attnums = adjust_inherited_attnums_multilevel(root, attnums,
appinfo->parent_relid,
top_parent_relid);
/* Now translate for this child */
return adjust_inherited_attnums(attnums, appinfo);
}
/*
* get_translated_update_targetlist
* Get the processed_tlist of an UPDATE query, translated as needed to
* match a child target relation.
*
* Optionally also return the list of target column numbers translated
* to this target relation. (The resnos in processed_tlist MUST NOT be
* relied on for this purpose.)
*/
void
get_translated_update_targetlist(PlannerInfo *root, Index relid,
List **processed_tlist, List **update_colnos)
{
/* This is pretty meaningless for commands other than UPDATE. */
Assert(root->parse->commandType == CMD_UPDATE);
if (relid == root->parse->resultRelation)
{
/*
* Non-inheritance case, so it's easy. The caller might be expecting
* a tree it can scribble on, though, so copy.
*/
*processed_tlist = copyObject(root->processed_tlist);
if (update_colnos)
*update_colnos = copyObject(root->update_colnos);
}
else
{
Assert(bms_is_member(relid, root->all_result_relids));
*processed_tlist = (List *)
adjust_appendrel_attrs_multilevel(root,
(Node *) root->processed_tlist,
find_base_rel(root, relid),
find_base_rel(root, root->parse->resultRelation));
if (update_colnos)
*update_colnos =
adjust_inherited_attnums_multilevel(root, root->update_colnos,
relid,
root->parse->resultRelation);
}
}
/*
* find_appinfos_by_relids
* Find AppendRelInfo structures for base relations listed in relids.
*
* The relids argument is typically a join relation's relids, which can
* include outer-join RT indexes in addition to baserels. We silently
* ignore the outer joins.
*
* The AppendRelInfos are returned in an array, which can be pfree'd by the
* caller. *nappinfos is set to the number of entries in the array.
*/
AppendRelInfo **
find_appinfos_by_relids(PlannerInfo *root, Relids relids, int *nappinfos)
{
AppendRelInfo **appinfos;
int cnt = 0;
int i;
/* Allocate an array that's certainly big enough */
appinfos = (AppendRelInfo **)
palloc(sizeof(AppendRelInfo *) * bms_num_members(relids));
i = -1;
while ((i = bms_next_member(relids, i)) >= 0)
{
AppendRelInfo *appinfo = root->append_rel_array[i];
if (!appinfo)
{
/* Probably i is an OJ index, but let's check */
if (find_base_rel_ignore_join(root, i) == NULL)
continue;
/* It's a base rel, but we lack an append_rel_array entry */
elog(ERROR, "child rel %d not found in append_rel_array", i);
}
appinfos[cnt++] = appinfo;
}
*nappinfos = cnt;
return appinfos;
}
/*****************************************************************************
*
* ROW-IDENTITY VARIABLE MANAGEMENT
*
* This code lacks a good home, perhaps. We choose to keep it here because
* adjust_appendrel_attrs_mutator() is its principal co-conspirator. That
* function does most of what is needed to expand ROWID_VAR Vars into the
* right things.
*
*****************************************************************************/
/*
* add_row_identity_var
* Register a row-identity column to be used in UPDATE/DELETE/MERGE.
*
* The Var must be equal(), aside from varno, to any other row-identity
* column with the same rowid_name. Thus, for example, "wholerow"
* row identities had better use vartype == RECORDOID.
*
* rtindex is currently redundant with rowid_var->varno, but we specify
* it as a separate parameter in case this is ever generalized to support
* non-Var expressions. (We could reasonably handle expressions over
* Vars of the specified rtindex, but for now that seems unnecessary.)
*/
void
add_row_identity_var(PlannerInfo *root, Var *orig_var,
Index rtindex, const char *rowid_name)
{
TargetEntry *tle;
Var *rowid_var;
RowIdentityVarInfo *ridinfo;
ListCell *lc;
/* For now, the argument must be just a Var of the given rtindex */
Assert(IsA(orig_var, Var));
Assert(orig_var->varno == rtindex);
Assert(orig_var->varlevelsup == 0);
Assert(orig_var->varnullingrels == NULL);
/*
* If we're doing non-inherited UPDATE/DELETE/MERGE, there's little need
* for ROWID_VAR shenanigans. Just shove the presented Var into the
* processed_tlist, and we're done.
*/
if (rtindex == root->parse->resultRelation)
{
tle = makeTargetEntry((Expr *) orig_var,
list_length(root->processed_tlist) + 1,
pstrdup(rowid_name),
true);
root->processed_tlist = lappend(root->processed_tlist, tle);
return;
}
/*
* Otherwise, rtindex should reference a leaf target relation that's being
* added to the query during expand_inherited_rtentry().
*/
Assert(bms_is_member(rtindex, root->leaf_result_relids));
Assert(root->append_rel_array[rtindex] != NULL);
/*
* We have to find a matching RowIdentityVarInfo, or make one if there is
* none. To allow using equal() to match the vars, change the varno to
* ROWID_VAR, leaving all else alone.
*/
rowid_var = copyObject(orig_var);
/* This could eventually become ChangeVarNodes() */
rowid_var->varno = ROWID_VAR;
/* Look for an existing row-id column of the same name */
foreach(lc, root->row_identity_vars)
{
ridinfo = (RowIdentityVarInfo *) lfirst(lc);
if (strcmp(rowid_name, ridinfo->rowidname) != 0)
continue;
if (equal(rowid_var, ridinfo->rowidvar))
{
/* Found a match; we need only record that rtindex needs it too */
ridinfo->rowidrels = bms_add_member(ridinfo->rowidrels, rtindex);
return;
}
else
{
/* Ooops, can't handle this */
elog(ERROR, "conflicting uses of row-identity name \"%s\"",
rowid_name);
}
}
/* No request yet, so add a new RowIdentityVarInfo */
ridinfo = makeNode(RowIdentityVarInfo);
ridinfo->rowidvar = copyObject(rowid_var);
/* for the moment, estimate width using just the datatype info */
ridinfo->rowidwidth = get_typavgwidth(exprType((Node *) rowid_var),
exprTypmod((Node *) rowid_var));
ridinfo->rowidname = pstrdup(rowid_name);
ridinfo->rowidrels = bms_make_singleton(rtindex);
root->row_identity_vars = lappend(root->row_identity_vars, ridinfo);
/* Change rowid_var into a reference to this row_identity_vars entry */
rowid_var->varattno = list_length(root->row_identity_vars);
/* Push the ROWID_VAR reference variable into processed_tlist */
tle = makeTargetEntry((Expr *) rowid_var,
list_length(root->processed_tlist) + 1,
pstrdup(rowid_name),
true);
root->processed_tlist = lappend(root->processed_tlist, tle);
}
/*
* add_row_identity_columns
*
* This function adds the row identity columns needed by the core code.
* FDWs might call add_row_identity_var() for themselves to add nonstandard
* columns. (Duplicate requests are fine.)
*/
void
add_row_identity_columns(PlannerInfo *root, Index rtindex,
RangeTblEntry *target_rte,
Relation target_relation)
{
CmdType commandType = root->parse->commandType;
char relkind = target_relation->rd_rel->relkind;
Var *var;
Assert(commandType == CMD_UPDATE || commandType == CMD_DELETE || commandType == CMD_MERGE);
if (commandType == CMD_MERGE ||
relkind == RELKIND_RELATION ||
relkind == RELKIND_MATVIEW ||
relkind == RELKIND_PARTITIONED_TABLE)
{
/*
* Emit CTID so that executor can find the row to merge, update or
* delete.
*/
var = makeVar(rtindex,
SelfItemPointerAttributeNumber,
TIDOID,
-1,
InvalidOid,
0);
add_row_identity_var(root, var, rtindex, "ctid");
}
else if (relkind == RELKIND_FOREIGN_TABLE)
{
/*
* Let the foreign table's FDW add whatever junk TLEs it wants.
*/
FdwRoutine *fdwroutine;
fdwroutine = GetFdwRoutineForRelation(target_relation, false);
if (fdwroutine->AddForeignUpdateTargets != NULL)
fdwroutine->AddForeignUpdateTargets(root, rtindex,
target_rte, target_relation);
/*
* For UPDATE, we need to make the FDW fetch unchanged columns by
* asking it to fetch a whole-row Var. That's because the top-level
* targetlist only contains entries for changed columns, but
* ExecUpdate will need to build the complete new tuple. (Actually,
* we only really need this in UPDATEs that are not pushed to the
* remote side, but it's hard to tell if that will be the case at the
* point when this function is called.)
*
* We will also need the whole row if there are any row triggers, so
* that the executor will have the "old" row to pass to the trigger.
* Alas, this misses system columns.
*/
if (commandType == CMD_UPDATE ||
(target_relation->trigdesc &&
(target_relation->trigdesc->trig_delete_after_row ||
target_relation->trigdesc->trig_delete_before_row)))
{
var = makeVar(rtindex,
InvalidAttrNumber,
RECORDOID,
-1,
InvalidOid,
0);
add_row_identity_var(root, var, rtindex, "wholerow");
}
}
}
/*
* distribute_row_identity_vars
*
* After we have finished identifying all the row identity columns
* needed by an inherited UPDATE/DELETE/MERGE query, make sure that
* these columns will be generated by all the target relations.
*
* This is more or less like what build_base_rel_tlists() does,
* except that it would not understand what to do with ROWID_VAR Vars.
* Since that function runs before inheritance relations are expanded,
* it will never see any such Vars anyway.
*/
void
distribute_row_identity_vars(PlannerInfo *root)
{
Query *parse = root->parse;
int result_relation = parse->resultRelation;
RangeTblEntry *target_rte;
RelOptInfo *target_rel;
ListCell *lc;
/*
* There's nothing to do if this isn't an inherited UPDATE/DELETE/MERGE.
*/
if (parse->commandType != CMD_UPDATE && parse->commandType != CMD_DELETE &&
parse->commandType != CMD_MERGE)
{
Assert(root->row_identity_vars == NIL);
return;
}
target_rte = rt_fetch(result_relation, parse->rtable);
if (!target_rte->inh)
{
Assert(root->row_identity_vars == NIL);
return;
}
/*
* Ordinarily, we expect that leaf result relation(s) will have added some
* ROWID_VAR Vars to the query. However, it's possible that constraint
* exclusion suppressed every leaf relation. The executor will get upset
* if the plan has no row identity columns at all, even though it will
* certainly process no rows. Handle this edge case by re-opening the top
* result relation and adding the row identity columns it would have used,
* as preprocess_targetlist() would have done if it weren't marked "inh".
* Then re-run build_base_rel_tlists() to ensure that the added columns
* get propagated to the relation's reltarget. (This is a bit ugly, but
* it seems better to confine the ugliness and extra cycles to this
* unusual corner case.)
*/
if (root->row_identity_vars == NIL)
{
Relation target_relation;
target_relation = table_open(target_rte->relid, NoLock);
add_row_identity_columns(root, result_relation,
target_rte, target_relation);
table_close(target_relation, NoLock);
build_base_rel_tlists(root, root->processed_tlist);
/* There are no ROWID_VAR Vars in this case, so we're done. */
return;
}
/*
* Dig through the processed_tlist to find the ROWID_VAR reference Vars,
* and forcibly copy them into the reltarget list of the topmost target
* relation. That's sufficient because they'll be copied to the
* individual leaf target rels (with appropriate translation) later,
* during appendrel expansion --- see set_append_rel_size().
*/
target_rel = find_base_rel(root, result_relation);
foreach(lc, root->processed_tlist)
{
TargetEntry *tle = lfirst(lc);
Var *var = (Var *) tle->expr;
if (var && IsA(var, Var) && var->varno == ROWID_VAR)
{
target_rel->reltarget->exprs =
lappend(target_rel->reltarget->exprs, copyObject(var));
/* reltarget cost and width will be computed later */
}
}
}
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