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Diffstat (limited to 'src/backend/optimizer/util/appendinfo.c')
| -rw-r--r-- | src/backend/optimizer/util/appendinfo.c | 1002 |
1 files changed, 1002 insertions, 0 deletions
diff --git a/src/backend/optimizer/util/appendinfo.c b/src/backend/optimizer/util/appendinfo.c new file mode 100644 index 0000000..af46f58 --- /dev/null +++ b/src/backend/optimizer/util/appendinfo.c @@ -0,0 +1,1002 @@ +/*------------------------------------------------------------------------- + * + * appendinfo.c + * Routines for mapping between append parent(s) and children + * + * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * src/backend/optimizer/path/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 "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 */ + + 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)); + 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; + + 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; + /* 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, context->nappinfos, + context->appinfos); + 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 */ + 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->nullable_relids = adjust_child_relids(oldinfo->nullable_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 a toplevel appendrel parent down to a child. + * + * In some cases we need to translate expressions referencing a parent relation + * to reference an appendrel child that's multiple levels removed from it. + */ +Node * +adjust_appendrel_attrs_multilevel(PlannerInfo *root, Node *node, + Relids child_relids, + Relids top_parent_relids) +{ + AppendRelInfo **appinfos; + Bitmapset *parent_relids = NULL; + int nappinfos; + int cnt; + + Assert(bms_num_members(child_relids) == bms_num_members(top_parent_relids)); + + appinfos = find_appinfos_by_relids(root, child_relids, &nappinfos); + + /* Construct relids set for the immediate parent of given child. */ + for (cnt = 0; cnt < nappinfos; cnt++) + { + AppendRelInfo *appinfo = appinfos[cnt]; + + parent_relids = bms_add_member(parent_relids, appinfo->parent_relid); + } + + /* Recurse if immediate parent is not the top parent. */ + if (!bms_equal(parent_relids, top_parent_relids)) + node = adjust_appendrel_attrs_multilevel(root, node, parent_relids, + top_parent_relids); + + /* Now translate for this child */ + 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; +} + +/* + * Replace any relid present in top_parent_relids with its child in + * child_relids. Members of child_relids can be multiple levels below top + * parent in the partition hierarchy. + */ +Relids +adjust_child_relids_multilevel(PlannerInfo *root, Relids relids, + Relids child_relids, Relids top_parent_relids) +{ + AppendRelInfo **appinfos; + int nappinfos; + Relids parent_relids = NULL; + Relids result; + Relids tmp_result = NULL; + int cnt; + + /* + * If the given relids set doesn't contain any of the top parent relids, + * it will remain unchanged. + */ + if (!bms_overlap(relids, top_parent_relids)) + return relids; + + appinfos = find_appinfos_by_relids(root, child_relids, &nappinfos); + + /* Construct relids set for the immediate parent of the given child. */ + for (cnt = 0; cnt < nappinfos; cnt++) + { + AppendRelInfo *appinfo = appinfos[cnt]; + + parent_relids = bms_add_member(parent_relids, appinfo->parent_relid); + } + + /* Recurse if immediate parent is not the top parent. */ + if (!bms_equal(parent_relids, top_parent_relids)) + { + tmp_result = adjust_child_relids_multilevel(root, relids, + parent_relids, + top_parent_relids); + relids = tmp_result; + } + + result = adjust_child_relids(relids, nappinfos, appinfos); + + /* Free memory consumed by any intermediate result. */ + if (tmp_result) + bms_free(tmp_result); + bms_free(parent_relids); + pfree(appinfos); + + return result; +} + +/* + * 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, + bms_make_singleton(relid), + bms_make_singleton(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 all relations specified by relids. + * + * 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; + + *nappinfos = bms_num_members(relids); + appinfos = (AppendRelInfo **) palloc(sizeof(AppendRelInfo *) * *nappinfos); + + i = -1; + while ((i = bms_next_member(relids, i)) >= 0) + { + AppendRelInfo *appinfo = root->append_rel_array[i]; + + if (!appinfo) + elog(ERROR, "child rel %d not found in append_rel_array", i); + + appinfos[cnt++] = appinfo; + } + 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. + * + * 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); + + /* + * If we're doing non-inherited UPDATE/DELETE, 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); + + if (relkind == RELKIND_RELATION || + relkind == RELKIND_MATVIEW || + relkind == RELKIND_PARTITIONED_TABLE) + { + /* + * Emit CTID so that executor can find the row to 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 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. */ + if (parse->commandType != CMD_UPDATE && parse->commandType != CMD_DELETE) + { + 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". + * (This is a bit ugly, but it seems better to confine the ugliness and + * extra cycles to this unusual corner case.) We needn't worry about + * fixing the rel's reltarget, as that won't affect the finished plan. + */ + 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); + 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 */ + } + } +} |