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Diffstat (limited to 'src/backend/parser/parse_merge.c')
| -rw-r--r-- | src/backend/parser/parse_merge.c | 654 |
1 files changed, 0 insertions, 654 deletions
diff --git a/src/backend/parser/parse_merge.c b/src/backend/parser/parse_merge.c deleted file mode 100644 index 722cb23b86c..00000000000 --- a/src/backend/parser/parse_merge.c +++ /dev/null @@ -1,654 +0,0 @@ -/*------------------------------------------------------------------------- - * - * parse_merge.c - * handle merge-statement in parser - * - * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group - * Portions Copyright (c) 1994, Regents of the University of California - * - * - * IDENTIFICATION - * src/backend/parser/parse_merge.c - * - *------------------------------------------------------------------------- - */ - -#include "postgres.h" - -#include "miscadmin.h" - -#include "access/sysattr.h" -#include "nodes/makefuncs.h" -#include "parser/analyze.h" -#include "parser/parse_collate.h" -#include "parser/parsetree.h" -#include "parser/parser.h" -#include "parser/parse_clause.h" -#include "parser/parse_cte.h" -#include "parser/parse_merge.h" -#include "parser/parse_relation.h" -#include "parser/parse_target.h" -#include "utils/rel.h" -#include "utils/relcache.h" - -static int transformMergeJoinClause(ParseState *pstate, Node *merge, - List **mergeSourceTargetList); -static void setNamespaceForMergeWhen(ParseState *pstate, - MergeWhenClause *mergeWhenClause); -static void setNamespaceVisibilityForRTE(List *namespace, RangeTblEntry *rte, - bool rel_visible, - bool cols_visible); -static List *expandSourceTL(ParseState *pstate, RangeTblEntry *rte, - int rtindex); - -/* - * Special handling for MERGE statement is required because we assemble - * the query manually. This is similar to setTargetTable() followed - * by transformFromClause() but with a few less steps. - * - * Process the FROM clause and add items to the query's range table, - * joinlist, and namespace. - * - * A special targetlist comprising of the columns from the right-subtree of - * the join is populated and returned. Note that when the JoinExpr is - * setup by transformMergeStmt, the left subtree has the target result - * relation and the right subtree has the source relation. - * - * Returns the rangetable index of the target relation. - */ -static int -transformMergeJoinClause(ParseState *pstate, Node *merge, - List **mergeSourceTargetList) -{ - RangeTblEntry *rte, - *rt_rte; - List *namespace; - int rtindex, - rt_rtindex; - Node *n; - int mergeTarget_relation = list_length(pstate->p_rtable) + 1; - Var *var; - TargetEntry *te; - - n = transformFromClauseItem(pstate, merge, - &rte, - &rtindex, - &rt_rte, - &rt_rtindex, - &namespace); - - pstate->p_joinlist = list_make1(n); - - /* - * We created an internal join between the target and the source relation - * to carry out the MERGE actions. Normally such an unaliased join hides - * the joining relations, unless the column references are qualified. - * Also, any unqualified column references are resolved to the Join RTE, if - * there is a matching entry in the targetlist. But the way MERGE - * execution is later setup, we expect all column references to resolve to - * either the source or the target relation. Hence we must not add the - * Join RTE to the namespace. - * - * The last entry must be for the top-level Join RTE. We don't want to - * resolve any references to the Join RTE. So discard that. - * - * We also do not want to resolve any references from the leftside of the - * Join since that corresponds to the target relation. References to the - * columns of the target relation must be resolved from the result - * relation and not the one that is used in the join. So the - * mergeTarget_relation is marked invisible to both qualified as well as - * unqualified references. - */ - Assert(list_length(namespace) > 1); - namespace = list_truncate(namespace, list_length(namespace) - 1); - pstate->p_namespace = list_concat(pstate->p_namespace, namespace); - - setNamespaceVisibilityForRTE(pstate->p_namespace, - rt_fetch(mergeTarget_relation, pstate->p_rtable), false, false); - - /* - * Expand the right relation and add its columns to the - * mergeSourceTargetList. Note that the right relation can either be a - * plain relation or a subquery or anything that can have a - * RangeTableEntry. - */ - *mergeSourceTargetList = expandSourceTL(pstate, rt_rte, rt_rtindex); - - /* - * Add a whole-row-Var entry to support references to "source.*". - */ - var = makeWholeRowVar(rt_rte, rt_rtindex, 0, false); - te = makeTargetEntry((Expr *) var, list_length(*mergeSourceTargetList) + 1, - NULL, true); - *mergeSourceTargetList = lappend(*mergeSourceTargetList, te); - - return mergeTarget_relation; -} - -/* - * Make appropriate changes to the namespace visibility while transforming - * individual action's quals and targetlist expressions. In particular, for - * INSERT actions we must only see the source relation (since INSERT action is - * invoked for NOT MATCHED tuples and hence there is no target tuple to deal - * with). On the other hand, UPDATE and DELETE actions can see both source and - * target relations. - * - * Also, since the internal Join node can hide the source and target - * relations, we must explicitly make the respective relation as visible so - * that columns can be referenced unqualified from these relations. - */ -static void -setNamespaceForMergeWhen(ParseState *pstate, MergeWhenClause *mergeWhenClause) -{ - RangeTblEntry *targetRelRTE, - *sourceRelRTE; - - /* Assume target relation is at index 1 */ - targetRelRTE = rt_fetch(1, pstate->p_rtable); - - /* - * Assume that the top-level join RTE is at the end. The source relation - * is just before that. - */ - sourceRelRTE = rt_fetch(list_length(pstate->p_rtable) - 1, pstate->p_rtable); - - switch (mergeWhenClause->commandType) - { - case CMD_INSERT: - - /* - * Inserts can't see target relation, but they can see source - * relation. - */ - setNamespaceVisibilityForRTE(pstate->p_namespace, - targetRelRTE, false, false); - setNamespaceVisibilityForRTE(pstate->p_namespace, - sourceRelRTE, true, true); - break; - - case CMD_UPDATE: - case CMD_DELETE: - - /* - * Updates and deletes can see both target and source relations. - */ - setNamespaceVisibilityForRTE(pstate->p_namespace, - targetRelRTE, true, true); - setNamespaceVisibilityForRTE(pstate->p_namespace, - sourceRelRTE, true, true); - break; - - case CMD_NOTHING: - break; - default: - elog(ERROR, "unknown action in MERGE WHEN clause"); - } -} - -/* - * transformMergeStmt - - * transforms a MERGE statement - */ -Query * -transformMergeStmt(ParseState *pstate, MergeStmt *stmt) -{ - Query *qry = makeNode(Query); - ListCell *l; - AclMode targetPerms = ACL_NO_RIGHTS; - bool is_terminal[2]; - JoinExpr *joinexpr; - RangeTblEntry *resultRelRTE, *mergeRelRTE; - List *mergeActionList; - - /* There can't be any outer WITH to worry about */ - Assert(pstate->p_ctenamespace == NIL); - - qry->commandType = CMD_MERGE; - qry->hasRecursive = false; - - /* process the WITH clause independently of all else */ - if (stmt->withClause) - { - if (stmt->withClause->recursive) - ereport(ERROR, - (errcode(ERRCODE_SYNTAX_ERROR), - errmsg("WITH RECURSIVE is not supported for MERGE statement"))); - - qry->cteList = transformWithClause(pstate, stmt->withClause); - qry->hasModifyingCTE = pstate->p_hasModifyingCTE; - } - - /* - * Check WHEN clauses for permissions and sanity - */ - is_terminal[0] = false; - is_terminal[1] = false; - foreach(l, stmt->mergeWhenClauses) - { - MergeWhenClause *mergeWhenClause = (MergeWhenClause *) lfirst(l); - int when_type = (mergeWhenClause->matched ? 0 : 1); - - /* - * Collect action types so we can check Target permissions - */ - switch (mergeWhenClause->commandType) - { - case CMD_INSERT: - targetPerms |= ACL_INSERT; - break; - case CMD_UPDATE: - targetPerms |= ACL_UPDATE; - break; - case CMD_DELETE: - targetPerms |= ACL_DELETE; - break; - case CMD_NOTHING: - break; - default: - elog(ERROR, "unknown action in MERGE WHEN clause"); - } - - /* - * Check for unreachable WHEN clauses - */ - if (mergeWhenClause->condition == NULL) - is_terminal[when_type] = true; - else if (is_terminal[when_type]) - ereport(ERROR, - (errcode(ERRCODE_SYNTAX_ERROR), - errmsg("unreachable WHEN clause specified after unconditional WHEN clause"))); - } - - /* - * Construct a query of the form - * SELECT relation.ctid --junk attribute - * ,relation.tableoid --junk attribute - * ,source_relation.<somecols> - * ,relation.<somecols> - * FROM relation RIGHT JOIN source_relation - * ON join_condition; -- no WHERE clause - all conditions are applied in - * executor - * - * stmt->relation is the target relation, given as a RangeVar - * stmt->source_relation is a RangeVar or subquery - * - * We specify the join as a RIGHT JOIN as a simple way of forcing the - * first (larg) RTE to refer to the target table. - * - * The MERGE query's join can be tuned in some cases, see below for these - * special case tweaks. - * - * We set QSRC_PARSER to show query constructed in parse analysis - * - * Note that we have only one Query for a MERGE statement and the planner - * is called only once. That query is executed once to produce our stream - * of candidate change rows, so the query must contain all of the columns - * required by each of the targetlist or conditions for each action. - * - * As top-level statements INSERT, UPDATE and DELETE have a Query, whereas - * with MERGE the individual actions do not require separate planning, - * only different handling in the executor. See nodeModifyTable handling - * of commandType CMD_MERGE. - * - * A sub-query can include the Target, but otherwise the sub-query cannot - * reference the outermost Target table at all. - */ - qry->querySource = QSRC_PARSER; - - /* - * Setup the target table. Unlike regular UPDATE/DELETE, we don't expand - * inheritance for the target relation in case of MERGE. - * - * This special arrangement is required for handling partitioned tables - * because we perform an JOIN between the target and the source relation to - * identify the matching and not-matching rows. If we take the usual path - * of expanding the target table's inheritance and create one subplan per - * partition, then we we won't be able to correctly identify the matching - * and not-matching rows since for a given source row, there may not be a - * matching row in one partition, but it may exists in some other - * partition. So we must first append all the qualifying rows from all the - * partitions and then do the matching. - * - * Once a target row is returned by the underlying join, we find the - * correct partition and setup required state to carry out UPDATE/DELETE. - * All of this happens during execution. - */ - qry->resultRelation = setTargetTable(pstate, stmt->relation, - false, /* do not expand inheritance */ - true, targetPerms); - - /* - * Create a JOIN between the target and the source relation. - */ - joinexpr = makeNode(JoinExpr); - joinexpr->isNatural = false; - joinexpr->alias = NULL; - joinexpr->usingClause = NIL; - joinexpr->quals = stmt->join_condition; - joinexpr->larg = (Node *) stmt->relation; - joinexpr->rarg = (Node *) stmt->source_relation; - - /* - * Simplify the MERGE query as much as possible - * - * These seem like things that could go into Optimizer, but they are - * semantic simplifications rather than optimizations, per se. - * - * If there are no INSERT actions we won't be using the non-matching - * candidate rows for anything, so no need for an outer join. We do still - * need an inner join for UPDATE and DELETE actions. - */ - if (targetPerms & ACL_INSERT) - joinexpr->jointype = JOIN_RIGHT; - else - joinexpr->jointype = JOIN_INNER; - - /* - * We use a special purpose transformation here because the normal - * routines don't quite work right for the MERGE case. - * - * A special mergeSourceTargetList is setup by transformMergeJoinClause(). - * It refers to all the attributes provided by the source relation. This - * is later used by set_plan_refs() to fix the UPDATE/INSERT target lists - * to so that they can correctly fetch the attributes from the source - * relation. - * - * The target relation when used in the underlying join, gets a new RTE - * with rte->inh set to true. We remember this RTE (and later pass on to - * the planner and executor) for two main reasons: - * - * 1. If we ever need to run EvalPlanQual while performing MERGE, we must - * make the modified tuple available to the underlying join query, which is - * using a different RTE from the resultRelation RTE. - * - * 2. rewriteTargetListMerge() requires the RTE of the underlying join in - * order to add junk CTID and TABLEOID attributes. - */ - qry->mergeTarget_relation = transformMergeJoinClause(pstate, (Node *) joinexpr, - &qry->mergeSourceTargetList); - - /* - * The target table referenced in the MERGE is looked up twice; once while - * setting it up as the result relation and again when it's used in the - * underlying the join query. In some rare situations, it may happen that - * these lookups return different results, for example, if a new relation - * with the same name gets created in a schema which is ahead in the - * search_path, in between the two lookups. - * - * It's a very narrow case, but nevertheless we guard against it by simply - * checking if the OIDs returned by the two lookups is the same. If not, we - * just throw an error. - */ - Assert(qry->resultRelation > 0); - Assert(qry->mergeTarget_relation > 0); - - /* Fetch both the RTEs */ - resultRelRTE = rt_fetch(qry->resultRelation, pstate->p_rtable); - mergeRelRTE = rt_fetch(qry->mergeTarget_relation, pstate->p_rtable); - - if (resultRelRTE->relid != mergeRelRTE->relid) - ereport(ERROR, - (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), - errmsg("relation referenced by MERGE statement has changed"))); - - /* - * This query should just provide the source relation columns. Later, in - * preprocess_targetlist(), we shall also add "ctid" attribute of the - * target relation to ensure that the target tuple can be fetched - * correctly. - */ - qry->targetList = qry->mergeSourceTargetList; - - /* qry has no WHERE clause so absent quals are shown as NULL */ - qry->jointree = makeFromExpr(pstate->p_joinlist, NULL); - qry->rtable = pstate->p_rtable; - - /* - * XXX MERGE is unsupported in various cases - */ - if (!(pstate->p_target_relation->rd_rel->relkind == RELKIND_RELATION || - pstate->p_target_relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)) - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("MERGE is not supported for this relation type"))); - - if (pstate->p_target_relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE && - pstate->p_target_relation->rd_rel->relhassubclass) - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("MERGE is not supported for relations with inheritance"))); - - if (pstate->p_target_relation->rd_rel->relhasrules) - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("MERGE is not supported for relations with rules"))); - - /* - * We now have a good query shape, so now look at the when conditions and - * action targetlists. - * - * Overall, the MERGE Query's targetlist is NIL. - * - * Each individual action has its own targetlist that needs separate - * transformation. These transforms don't do anything to the overall - * targetlist, since that is only used for resjunk columns. - * - * We can reference any column in Target or Source, which is OK because - * both of those already have RTEs. There is nothing like the EXCLUDED - * pseudo-relation for INSERT ON CONFLICT. - */ - mergeActionList = NIL; - foreach(l, stmt->mergeWhenClauses) - { - MergeWhenClause *mergeWhenClause = (MergeWhenClause *) lfirst(l); - MergeAction *action = makeNode(MergeAction); - - action->commandType = mergeWhenClause->commandType; - action->matched = mergeWhenClause->matched; - - /* - * Set namespace for the specific action. This must be done before - * analyzing the WHEN quals and the action targetlisst. - */ - setNamespaceForMergeWhen(pstate, mergeWhenClause); - - /* - * Transform the when condition. - * - * Note that these quals are NOT added to the join quals; instead they - * are evaluated separately during execution to decide which of the - * WHEN MATCHED or WHEN NOT MATCHED actions to execute. - */ - action->qual = transformWhereClause(pstate, mergeWhenClause->condition, - EXPR_KIND_MERGE_WHEN_AND, "WHEN"); - - /* - * Transform target lists for each INSERT and UPDATE action stmt - */ - switch (action->commandType) - { - case CMD_INSERT: - { - List *exprList = NIL; - ListCell *lc; - RangeTblEntry *rte; - ListCell *icols; - ListCell *attnos; - List *icolumns; - List *attrnos; - - pstate->p_is_insert = true; - - icolumns = checkInsertTargets(pstate, - mergeWhenClause->cols, - &attrnos); - Assert(list_length(icolumns) == list_length(attrnos)); - - action->override = mergeWhenClause->override; - - /* - * Handle INSERT much like in transformInsertStmt - */ - if (mergeWhenClause->values == NIL) - { - /* - * We have INSERT ... DEFAULT VALUES. We can handle - * this case by emitting an empty targetlist --- all - * columns will be defaulted when the planner expands - * the targetlist. - */ - exprList = NIL; - } - else - { - /* - * Process INSERT ... VALUES with a single VALUES - * sublist. We treat this case separately for - * efficiency. The sublist is just computed directly - * as the Query's targetlist, with no VALUES RTE. So - * it works just like a SELECT without any FROM. - */ - - /* - * Do basic expression transformation (same as a ROW() - * expr, but allow SetToDefault at top level) - */ - exprList = transformExpressionList(pstate, - mergeWhenClause->values, - EXPR_KIND_VALUES_SINGLE, - true); - - /* Prepare row for assignment to target table */ - exprList = transformInsertRow(pstate, exprList, - mergeWhenClause->cols, - icolumns, attrnos, - false); - } - - /* - * Generate action's target list using the computed list - * of expressions. Also, mark all the target columns as - * needing insert permissions. - */ - rte = pstate->p_target_rangetblentry; - icols = list_head(icolumns); - attnos = list_head(attrnos); - foreach(lc, exprList) - { - Expr *expr = (Expr *) lfirst(lc); - ResTarget *col; - AttrNumber attr_num; - TargetEntry *tle; - - col = lfirst_node(ResTarget, icols); - attr_num = (AttrNumber) lfirst_int(attnos); - - tle = makeTargetEntry(expr, - attr_num, - col->name, - false); - action->targetList = lappend(action->targetList, tle); - - rte->insertedCols = bms_add_member(rte->insertedCols, - attr_num - FirstLowInvalidHeapAttributeNumber); - - icols = lnext(icols); - attnos = lnext(attnos); - } - } - break; - case CMD_UPDATE: - { - pstate->p_is_insert = false; - action->targetList = transformUpdateTargetList(pstate, - mergeWhenClause->targetList); - } - break; - case CMD_DELETE: - break; - - case CMD_NOTHING: - action->targetList = NIL; - break; - default: - elog(ERROR, "unknown action in MERGE WHEN clause"); - } - - mergeActionList = lappend(mergeActionList, action); - } - - qry->mergeActionList = mergeActionList; - - /* XXX maybe later */ - qry->returningList = NULL; - - qry->hasTargetSRFs = false; - qry->hasSubLinks = pstate->p_hasSubLinks; - - assign_query_collations(pstate, qry); - - return qry; -} - -static void -setNamespaceVisibilityForRTE(List *namespace, RangeTblEntry *rte, - bool rel_visible, - bool cols_visible) -{ - ListCell *lc; - - foreach(lc, namespace) - { - ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(lc); - - if (nsitem->p_rte == rte) - { - nsitem->p_rel_visible = rel_visible; - nsitem->p_cols_visible = cols_visible; - break; - } - } - -} - -/* - * Expand the source relation to include all attributes of this RTE. - * - * This function is very similar to expandRelAttrs except that we don't mark - * columns for SELECT privileges. That will be decided later when we transform - * the action targetlists and the WHEN quals for actual references to the - * source relation. - */ -static List * -expandSourceTL(ParseState *pstate, RangeTblEntry *rte, int rtindex) -{ - List *names, - *vars; - ListCell *name, - *var; - List *te_list = NIL; - - expandRTE(rte, rtindex, 0, -1, false, &names, &vars); - - /* - * Require read access to the table. - */ - rte->requiredPerms |= ACL_SELECT; - - forboth(name, names, var, vars) - { - char *label = strVal(lfirst(name)); - Var *varnode = (Var *) lfirst(var); - TargetEntry *te; - - te = makeTargetEntry((Expr *) varnode, - (AttrNumber) pstate->p_next_resno++, - label, - false); - te_list = lappend(te_list, te); - } - - Assert(name == NULL && var == NULL); /* lists not the same length? */ - - return te_list; -} |