/*------------------------------------------------------------------------- * * 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 */ } } }