summaryrefslogtreecommitdiffstats
path: root/src/backend/optimizer/prep/preptlist.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/backend/optimizer/prep/preptlist.c')
-rw-r--r--src/backend/optimizer/prep/preptlist.c437
1 files changed, 437 insertions, 0 deletions
diff --git a/src/backend/optimizer/prep/preptlist.c b/src/backend/optimizer/prep/preptlist.c
new file mode 100644
index 0000000..d56d8c6
--- /dev/null
+++ b/src/backend/optimizer/prep/preptlist.c
@@ -0,0 +1,437 @@
+/*-------------------------------------------------------------------------
+ *
+ * preptlist.c
+ * Routines to preprocess the parse tree target list
+ *
+ * For INSERT and UPDATE queries, the targetlist must contain an entry for
+ * each attribute of the target relation in the correct order. For UPDATE and
+ * DELETE queries, it must also contain junk tlist entries needed to allow the
+ * executor to identify the rows to be updated or deleted. For all query
+ * types, we may need to add junk tlist entries for Vars used in the RETURNING
+ * list and row ID information needed for SELECT FOR UPDATE locking and/or
+ * EvalPlanQual checking.
+ *
+ * The query rewrite phase also does preprocessing of the targetlist (see
+ * rewriteTargetListIU). The division of labor between here and there is
+ * partially historical, but it's not entirely arbitrary. In particular,
+ * consider an UPDATE across an inheritance tree. What rewriteTargetListIU
+ * does need be done only once (because it depends only on the properties of
+ * the parent relation). What's done here has to be done over again for each
+ * child relation, because it depends on the properties of the child, which
+ * might be of a different relation type, or have more columns and/or a
+ * different column order than the parent.
+ *
+ * The fact that rewriteTargetListIU sorts non-resjunk tlist entries by column
+ * position, which expand_targetlist depends on, violates the above comment
+ * because the sorting is only valid for the parent relation. In inherited
+ * UPDATE cases, adjust_inherited_tlist runs in between to take care of fixing
+ * the tlists for child tables to keep expand_targetlist happy. We do it like
+ * that because it's faster in typical non-inherited cases.
+ *
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ * src/backend/optimizer/prep/preptlist.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/sysattr.h"
+#include "access/table.h"
+#include "catalog/pg_type.h"
+#include "nodes/makefuncs.h"
+#include "optimizer/optimizer.h"
+#include "optimizer/prep.h"
+#include "optimizer/tlist.h"
+#include "parser/parse_coerce.h"
+#include "parser/parsetree.h"
+#include "rewrite/rewriteHandler.h"
+#include "utils/rel.h"
+
+static List *expand_targetlist(List *tlist, int command_type,
+ Index result_relation, Relation rel);
+
+
+/*
+ * preprocess_targetlist
+ * Driver for preprocessing the parse tree targetlist.
+ *
+ * Returns the new targetlist.
+ *
+ * As a side effect, if there's an ON CONFLICT UPDATE clause, its targetlist
+ * is also preprocessed (and updated in-place).
+ */
+List *
+preprocess_targetlist(PlannerInfo *root)
+{
+ Query *parse = root->parse;
+ int result_relation = parse->resultRelation;
+ List *range_table = parse->rtable;
+ CmdType command_type = parse->commandType;
+ RangeTblEntry *target_rte = NULL;
+ Relation target_relation = NULL;
+ List *tlist;
+ ListCell *lc;
+
+ /*
+ * If there is a result relation, open it so we can look for missing
+ * columns and so on. We assume that previous code already acquired at
+ * least AccessShareLock on the relation, so we need no lock here.
+ */
+ if (result_relation)
+ {
+ target_rte = rt_fetch(result_relation, range_table);
+
+ /*
+ * Sanity check: it'd better be a real relation not, say, a subquery.
+ * Else parser or rewriter messed up.
+ */
+ if (target_rte->rtekind != RTE_RELATION)
+ elog(ERROR, "result relation must be a regular relation");
+
+ target_relation = table_open(target_rte->relid, NoLock);
+ }
+ else
+ Assert(command_type == CMD_SELECT);
+
+ /*
+ * For UPDATE/DELETE, add any junk column(s) needed to allow the executor
+ * to identify the rows to be updated or deleted. Note that this step
+ * scribbles on parse->targetList, which is not very desirable, but we
+ * keep it that way to avoid changing APIs used by FDWs.
+ */
+ if (command_type == CMD_UPDATE || command_type == CMD_DELETE)
+ rewriteTargetListUD(parse, target_rte, target_relation);
+
+ /*
+ * for heap_form_tuple to work, the targetlist must match the exact order
+ * of the attributes. We also need to fill in any missing attributes. -ay
+ * 10/94
+ */
+ tlist = parse->targetList;
+ if (command_type == CMD_INSERT || command_type == CMD_UPDATE)
+ tlist = expand_targetlist(tlist, command_type,
+ result_relation, target_relation);
+
+ /*
+ * Add necessary junk columns for rowmarked rels. These values are needed
+ * for locking of rels selected FOR UPDATE/SHARE, and to do EvalPlanQual
+ * rechecking. See comments for PlanRowMark in plannodes.h. If you
+ * change this stanza, see also expand_inherited_rtentry(), which has to
+ * be able to add on junk columns equivalent to these.
+ */
+ foreach(lc, root->rowMarks)
+ {
+ PlanRowMark *rc = (PlanRowMark *) lfirst(lc);
+ Var *var;
+ char resname[32];
+ TargetEntry *tle;
+
+ /* child rels use the same junk attrs as their parents */
+ if (rc->rti != rc->prti)
+ continue;
+
+ if (rc->allMarkTypes & ~(1 << ROW_MARK_COPY))
+ {
+ /* Need to fetch TID */
+ var = makeVar(rc->rti,
+ SelfItemPointerAttributeNumber,
+ TIDOID,
+ -1,
+ InvalidOid,
+ 0);
+ snprintf(resname, sizeof(resname), "ctid%u", rc->rowmarkId);
+ tle = makeTargetEntry((Expr *) var,
+ list_length(tlist) + 1,
+ pstrdup(resname),
+ true);
+ tlist = lappend(tlist, tle);
+ }
+ if (rc->allMarkTypes & (1 << ROW_MARK_COPY))
+ {
+ /* Need the whole row as a junk var */
+ var = makeWholeRowVar(rt_fetch(rc->rti, range_table),
+ rc->rti,
+ 0,
+ false);
+ snprintf(resname, sizeof(resname), "wholerow%u", rc->rowmarkId);
+ tle = makeTargetEntry((Expr *) var,
+ list_length(tlist) + 1,
+ pstrdup(resname),
+ true);
+ tlist = lappend(tlist, tle);
+ }
+
+ /* If parent of inheritance tree, always fetch the tableoid too. */
+ if (rc->isParent)
+ {
+ var = makeVar(rc->rti,
+ TableOidAttributeNumber,
+ OIDOID,
+ -1,
+ InvalidOid,
+ 0);
+ snprintf(resname, sizeof(resname), "tableoid%u", rc->rowmarkId);
+ tle = makeTargetEntry((Expr *) var,
+ list_length(tlist) + 1,
+ pstrdup(resname),
+ true);
+ tlist = lappend(tlist, tle);
+ }
+ }
+
+ /*
+ * If the query has a RETURNING list, add resjunk entries for any Vars
+ * used in RETURNING that belong to other relations. We need to do this
+ * to make these Vars available for the RETURNING calculation. Vars that
+ * belong to the result rel don't need to be added, because they will be
+ * made to refer to the actual heap tuple.
+ */
+ if (parse->returningList && list_length(parse->rtable) > 1)
+ {
+ List *vars;
+ ListCell *l;
+
+ vars = pull_var_clause((Node *) parse->returningList,
+ PVC_RECURSE_AGGREGATES |
+ PVC_RECURSE_WINDOWFUNCS |
+ PVC_INCLUDE_PLACEHOLDERS);
+ foreach(l, vars)
+ {
+ Var *var = (Var *) lfirst(l);
+ TargetEntry *tle;
+
+ if (IsA(var, Var) &&
+ var->varno == result_relation)
+ continue; /* don't need it */
+
+ if (tlist_member((Expr *) var, tlist))
+ continue; /* already got it */
+
+ tle = makeTargetEntry((Expr *) var,
+ list_length(tlist) + 1,
+ NULL,
+ true);
+
+ tlist = lappend(tlist, tle);
+ }
+ list_free(vars);
+ }
+
+ /*
+ * If there's an ON CONFLICT UPDATE clause, preprocess its targetlist too
+ * while we have the relation open.
+ */
+ if (parse->onConflict)
+ parse->onConflict->onConflictSet =
+ expand_targetlist(parse->onConflict->onConflictSet,
+ CMD_UPDATE,
+ result_relation,
+ target_relation);
+
+ if (target_relation)
+ table_close(target_relation, NoLock);
+
+ return tlist;
+}
+
+
+/*****************************************************************************
+ *
+ * TARGETLIST EXPANSION
+ *
+ *****************************************************************************/
+
+/*
+ * expand_targetlist
+ * Given a target list as generated by the parser and a result relation,
+ * add targetlist entries for any missing attributes, and ensure the
+ * non-junk attributes appear in proper field order.
+ */
+static List *
+expand_targetlist(List *tlist, int command_type,
+ Index result_relation, Relation rel)
+{
+ List *new_tlist = NIL;
+ ListCell *tlist_item;
+ int attrno,
+ numattrs;
+
+ tlist_item = list_head(tlist);
+
+ /*
+ * The rewriter should have already ensured that the TLEs are in correct
+ * order; but we have to insert TLEs for any missing attributes.
+ *
+ * Scan the tuple description in the relation's relcache entry to make
+ * sure we have all the user attributes in the right order.
+ */
+ numattrs = RelationGetNumberOfAttributes(rel);
+
+ for (attrno = 1; attrno <= numattrs; attrno++)
+ {
+ Form_pg_attribute att_tup = TupleDescAttr(rel->rd_att, attrno - 1);
+ TargetEntry *new_tle = NULL;
+
+ if (tlist_item != NULL)
+ {
+ TargetEntry *old_tle = (TargetEntry *) lfirst(tlist_item);
+
+ if (!old_tle->resjunk && old_tle->resno == attrno)
+ {
+ new_tle = old_tle;
+ tlist_item = lnext(tlist, tlist_item);
+ }
+ }
+
+ if (new_tle == NULL)
+ {
+ /*
+ * Didn't find a matching tlist entry, so make one.
+ *
+ * For INSERT, generate a NULL constant. (We assume the rewriter
+ * would have inserted any available default value.) Also, if the
+ * column isn't dropped, apply any domain constraints that might
+ * exist --- this is to catch domain NOT NULL.
+ *
+ * For UPDATE, generate a Var reference to the existing value of
+ * the attribute, so that it gets copied to the new tuple. But
+ * generate a NULL for dropped columns (we want to drop any old
+ * values).
+ *
+ * When generating a NULL constant for a dropped column, we label
+ * it INT4 (any other guaranteed-to-exist datatype would do as
+ * well). We can't label it with the dropped column's datatype
+ * since that might not exist anymore. It does not really matter
+ * what we claim the type is, since NULL is NULL --- its
+ * representation is datatype-independent. This could perhaps
+ * confuse code comparing the finished plan to the target
+ * relation, however.
+ */
+ Oid atttype = att_tup->atttypid;
+ int32 atttypmod = att_tup->atttypmod;
+ Oid attcollation = att_tup->attcollation;
+ Node *new_expr;
+
+ switch (command_type)
+ {
+ case CMD_INSERT:
+ if (!att_tup->attisdropped)
+ {
+ new_expr = (Node *) makeConst(atttype,
+ -1,
+ attcollation,
+ att_tup->attlen,
+ (Datum) 0,
+ true, /* isnull */
+ att_tup->attbyval);
+ new_expr = coerce_to_domain(new_expr,
+ InvalidOid, -1,
+ atttype,
+ COERCION_IMPLICIT,
+ COERCE_IMPLICIT_CAST,
+ -1,
+ false);
+ }
+ else
+ {
+ /* Insert NULL for dropped column */
+ new_expr = (Node *) makeConst(INT4OID,
+ -1,
+ InvalidOid,
+ sizeof(int32),
+ (Datum) 0,
+ true, /* isnull */
+ true /* byval */ );
+ }
+ break;
+ case CMD_UPDATE:
+ if (!att_tup->attisdropped)
+ {
+ new_expr = (Node *) makeVar(result_relation,
+ attrno,
+ atttype,
+ atttypmod,
+ attcollation,
+ 0);
+ }
+ else
+ {
+ /* Insert NULL for dropped column */
+ new_expr = (Node *) makeConst(INT4OID,
+ -1,
+ InvalidOid,
+ sizeof(int32),
+ (Datum) 0,
+ true, /* isnull */
+ true /* byval */ );
+ }
+ break;
+ default:
+ elog(ERROR, "unrecognized command_type: %d",
+ (int) command_type);
+ new_expr = NULL; /* keep compiler quiet */
+ break;
+ }
+
+ new_tle = makeTargetEntry((Expr *) new_expr,
+ attrno,
+ pstrdup(NameStr(att_tup->attname)),
+ false);
+ }
+
+ new_tlist = lappend(new_tlist, new_tle);
+ }
+
+ /*
+ * The remaining tlist entries should be resjunk; append them all to the
+ * end of the new tlist, making sure they have resnos higher than the last
+ * real attribute. (Note: although the rewriter already did such
+ * renumbering, we have to do it again here in case we are doing an UPDATE
+ * in a table with dropped columns, or an inheritance child table with
+ * extra columns.)
+ */
+ while (tlist_item)
+ {
+ TargetEntry *old_tle = (TargetEntry *) lfirst(tlist_item);
+
+ if (!old_tle->resjunk)
+ elog(ERROR, "targetlist is not sorted correctly");
+ /* Get the resno right, but don't copy unnecessarily */
+ if (old_tle->resno != attrno)
+ {
+ old_tle = flatCopyTargetEntry(old_tle);
+ old_tle->resno = attrno;
+ }
+ new_tlist = lappend(new_tlist, old_tle);
+ attrno++;
+ tlist_item = lnext(tlist, tlist_item);
+ }
+
+ return new_tlist;
+}
+
+
+/*
+ * Locate PlanRowMark for given RT index, or return NULL if none
+ *
+ * This probably ought to be elsewhere, but there's no very good place
+ */
+PlanRowMark *
+get_plan_rowmark(List *rowmarks, Index rtindex)
+{
+ ListCell *l;
+
+ foreach(l, rowmarks)
+ {
+ PlanRowMark *rc = (PlanRowMark *) lfirst(l);
+
+ if (rc->rti == rtindex)
+ return rc;
+ }
+ return NULL;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-07-30 09:44:47 +0000