Adding upstream version 16.2.upstream/16.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 637 insertions, 0 deletions

diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
new file mode 100644
index 0000000..e91920c
--- /dev/null
+++ b/src/backend/commands/createas.c
@@ -0,0 +1,637 @@
+/*-------------------------------------------------------------------------
+ *
+ * createas.c
+ *	  Execution of CREATE TABLE ... AS, a/k/a SELECT INTO.
+ *	  Since CREATE MATERIALIZED VIEW shares syntax and most behaviors,
+ *	  we implement that here, too.
+ *
+ * We implement this by diverting the query's normal output to a
+ * specialized DestReceiver type.
+ *
+ * Formerly, CTAS was implemented as a variant of SELECT, which led
+ * to assorted legacy behaviors that we still try to preserve, notably that
+ * we must return a tuples-processed count in the QueryCompletion.  (We no
+ * longer do that for CTAS ... WITH NO DATA, however.)
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/commands/createas.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/heapam.h"
+#include "access/htup_details.h"
+#include "access/reloptions.h"
+#include "access/sysattr.h"
+#include "access/tableam.h"
+#include "access/xact.h"
+#include "access/xlog.h"
+#include "catalog/namespace.h"
+#include "catalog/toasting.h"
+#include "commands/createas.h"
+#include "commands/matview.h"
+#include "commands/prepare.h"
+#include "commands/tablecmds.h"
+#include "commands/view.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "parser/parse_clause.h"
+#include "rewrite/rewriteHandler.h"
+#include "storage/smgr.h"
+#include "tcop/tcopprot.h"
+#include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/rls.h"
+#include "utils/snapmgr.h"
+
+typedef struct
+{
+	DestReceiver pub;			/* publicly-known function pointers */
+	IntoClause *into;			/* target relation specification */
+	/* These fields are filled by intorel_startup: */
+	Relation	rel;			/* relation to write to */
+	ObjectAddress reladdr;		/* address of rel, for ExecCreateTableAs */
+	CommandId	output_cid;		/* cmin to insert in output tuples */
+	int			ti_options;		/* table_tuple_insert performance options */
+	BulkInsertState bistate;	/* bulk insert state */
+} DR_intorel;
+
+/* utility functions for CTAS definition creation */
+static ObjectAddress create_ctas_internal(List *attrList, IntoClause *into);
+static ObjectAddress create_ctas_nodata(List *tlist, IntoClause *into);
+
+/* DestReceiver routines for collecting data */
+static void intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
+static bool intorel_receive(TupleTableSlot *slot, DestReceiver *self);
+static void intorel_shutdown(DestReceiver *self);
+static void intorel_destroy(DestReceiver *self);
+
+
+/*
+ * create_ctas_internal
+ *
+ * Internal utility used for the creation of the definition of a relation
+ * created via CREATE TABLE AS or a materialized view.  Caller needs to
+ * provide a list of attributes (ColumnDef nodes).
+ */
+static ObjectAddress
+create_ctas_internal(List *attrList, IntoClause *into)
+{
+	CreateStmt *create = makeNode(CreateStmt);
+	bool		is_matview;
+	char		relkind;
+	Datum		toast_options;
+	static char *validnsps[] = HEAP_RELOPT_NAMESPACES;
+	ObjectAddress intoRelationAddr;
+
+	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
+	is_matview = (into->viewQuery != NULL);
+	relkind = is_matview ? RELKIND_MATVIEW : RELKIND_RELATION;
+
+	/*
+	 * Create the target relation by faking up a CREATE TABLE parsetree and
+	 * passing it to DefineRelation.
+	 */
+	create->relation = into->rel;
+	create->tableElts = attrList;
+	create->inhRelations = NIL;
+	create->ofTypename = NULL;
+	create->constraints = NIL;
+	create->options = into->options;
+	create->oncommit = into->onCommit;
+	create->tablespacename = into->tableSpaceName;
+	create->if_not_exists = false;
+	create->accessMethod = into->accessMethod;
+
+	/*
+	 * Create the relation.  (This will error out if there's an existing view,
+	 * so we don't need more code to complain if "replace" is false.)
+	 */
+	intoRelationAddr = DefineRelation(create, relkind, InvalidOid, NULL, NULL);
+
+	/*
+	 * If necessary, create a TOAST table for the target table.  Note that
+	 * NewRelationCreateToastTable ends with CommandCounterIncrement(), so
+	 * that the TOAST table will be visible for insertion.
+	 */
+	CommandCounterIncrement();
+
+	/* parse and validate reloptions for the toast table */
+	toast_options = transformRelOptions((Datum) 0,
+										create->options,
+										"toast",
+										validnsps,
+										true, false);
+
+	(void) heap_reloptions(RELKIND_TOASTVALUE, toast_options, true);
+
+	NewRelationCreateToastTable(intoRelationAddr.objectId, toast_options);
+
+	/* Create the "view" part of a materialized view. */
+	if (is_matview)
+	{
+		/* StoreViewQuery scribbles on tree, so make a copy */
+		Query	   *query = (Query *) copyObject(into->viewQuery);
+
+		StoreViewQuery(intoRelationAddr.objectId, query, false);
+		CommandCounterIncrement();
+	}
+
+	return intoRelationAddr;
+}
+
+
+/*
+ * create_ctas_nodata
+ *
+ * Create CTAS or materialized view when WITH NO DATA is used, starting from
+ * the targetlist of the SELECT or view definition.
+ */
+static ObjectAddress
+create_ctas_nodata(List *tlist, IntoClause *into)
+{
+	List	   *attrList;
+	ListCell   *t,
+			   *lc;
+
+	/*
+	 * Build list of ColumnDefs from non-junk elements of the tlist.  If a
+	 * column name list was specified in CREATE TABLE AS, override the column
+	 * names in the query.  (Too few column names are OK, too many are not.)
+	 */
+	attrList = NIL;
+	lc = list_head(into->colNames);
+	foreach(t, tlist)
+	{
+		TargetEntry *tle = (TargetEntry *) lfirst(t);
+
+		if (!tle->resjunk)
+		{
+			ColumnDef  *col;
+			char	   *colname;
+
+			if (lc)
+			{
+				colname = strVal(lfirst(lc));
+				lc = lnext(into->colNames, lc);
+			}
+			else
+				colname = tle->resname;
+
+			col = makeColumnDef(colname,
+								exprType((Node *) tle->expr),
+								exprTypmod((Node *) tle->expr),
+								exprCollation((Node *) tle->expr));
+
+			/*
+			 * It's possible that the column is of a collatable type but the
+			 * collation could not be resolved, so double-check.  (We must
+			 * check this here because DefineRelation would adopt the type's
+			 * default collation rather than complaining.)
+			 */
+			if (!OidIsValid(col->collOid) &&
+				type_is_collatable(col->typeName->typeOid))
+				ereport(ERROR,
+						(errcode(ERRCODE_INDETERMINATE_COLLATION),
+						 errmsg("no collation was derived for column \"%s\" with collatable type %s",
+								col->colname,
+								format_type_be(col->typeName->typeOid)),
+						 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+			attrList = lappend(attrList, col);
+		}
+	}
+
+	if (lc != NULL)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("too many column names were specified")));
+
+	/* Create the relation definition using the ColumnDef list */
+	return create_ctas_internal(attrList, into);
+}
+
+
+/*
+ * ExecCreateTableAs -- execute a CREATE TABLE AS command
+ */
+ObjectAddress
+ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
+				  ParamListInfo params, QueryEnvironment *queryEnv,
+				  QueryCompletion *qc)
+{
+	Query	   *query = castNode(Query, stmt->query);
+	IntoClause *into = stmt->into;
+	bool		is_matview = (into->viewQuery != NULL);
+	DestReceiver *dest;
+	Oid			save_userid = InvalidOid;
+	int			save_sec_context = 0;
+	int			save_nestlevel = 0;
+	ObjectAddress address;
+	List	   *rewritten;
+	PlannedStmt *plan;
+	QueryDesc  *queryDesc;
+
+	/* Check if the relation exists or not */
+	if (CreateTableAsRelExists(stmt))
+		return InvalidObjectAddress;
+
+	/*
+	 * Create the tuple receiver object and insert info it will need
+	 */
+	dest = CreateIntoRelDestReceiver(into);
+
+	/*
+	 * The contained Query could be a SELECT, or an EXECUTE utility command.
+	 * If the latter, we just pass it off to ExecuteQuery.
+	 */
+	if (query->commandType == CMD_UTILITY &&
+		IsA(query->utilityStmt, ExecuteStmt))
+	{
+		ExecuteStmt *estmt = castNode(ExecuteStmt, query->utilityStmt);
+
+		Assert(!is_matview);	/* excluded by syntax */
+		ExecuteQuery(pstate, estmt, into, params, dest, qc);
+
+		/* get object address that intorel_startup saved for us */
+		address = ((DR_intorel *) dest)->reladdr;
+
+		return address;
+	}
+	Assert(query->commandType == CMD_SELECT);
+
+	/*
+	 * For materialized views, lock down security-restricted operations and
+	 * arrange to make GUC variable changes local to this command.  This is
+	 * not necessary for security, but this keeps the behavior similar to
+	 * REFRESH MATERIALIZED VIEW.  Otherwise, one could create a materialized
+	 * view not possible to refresh.
+	 */
+	if (is_matview)
+	{
+		GetUserIdAndSecContext(&save_userid, &save_sec_context);
+		SetUserIdAndSecContext(save_userid,
+							   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+		save_nestlevel = NewGUCNestLevel();
+	}
+
+	if (into->skipData)
+	{
+		/*
+		 * If WITH NO DATA was specified, do not go through the rewriter,
+		 * planner and executor.  Just define the relation using a code path
+		 * similar to CREATE VIEW.  This avoids dump/restore problems stemming
+		 * from running the planner before all dependencies are set up.
+		 */
+		address = create_ctas_nodata(query->targetList, into);
+	}
+	else
+	{
+		/*
+		 * Parse analysis was done already, but we still have to run the rule
+		 * rewriter.  We do not do AcquireRewriteLocks: we assume the query
+		 * either came straight from the parser, or suitable locks were
+		 * acquired by plancache.c.
+		 */
+		rewritten = QueryRewrite(query);
+
+		/* SELECT should never rewrite to more or less than one SELECT query */
+		if (list_length(rewritten) != 1)
+			elog(ERROR, "unexpected rewrite result for %s",
+				 is_matview ? "CREATE MATERIALIZED VIEW" :
+				 "CREATE TABLE AS SELECT");
+		query = linitial_node(Query, rewritten);
+		Assert(query->commandType == CMD_SELECT);
+
+		/* plan the query */
+		plan = pg_plan_query(query, pstate->p_sourcetext,
+							 CURSOR_OPT_PARALLEL_OK, params);
+
+		/*
+		 * Use a snapshot with an updated command ID to ensure this query sees
+		 * results of any previously executed queries.  (This could only
+		 * matter if the planner executed an allegedly-stable function that
+		 * changed the database contents, but let's do it anyway to be
+		 * parallel to the EXPLAIN code path.)
+		 */
+		PushCopiedSnapshot(GetActiveSnapshot());
+		UpdateActiveSnapshotCommandId();
+
+		/* Create a QueryDesc, redirecting output to our tuple receiver */
+		queryDesc = CreateQueryDesc(plan, pstate->p_sourcetext,
+									GetActiveSnapshot(), InvalidSnapshot,
+									dest, params, queryEnv, 0);
+
+		/* call ExecutorStart to prepare the plan for execution */
+		ExecutorStart(queryDesc, GetIntoRelEFlags(into));
+
+		/* run the plan to completion */
+		ExecutorRun(queryDesc, ForwardScanDirection, 0, true);
+
+		/* save the rowcount if we're given a qc to fill */
+		if (qc)
+			SetQueryCompletion(qc, CMDTAG_SELECT, queryDesc->estate->es_processed);
+
+		/* get object address that intorel_startup saved for us */
+		address = ((DR_intorel *) dest)->reladdr;
+
+		/* and clean up */
+		ExecutorFinish(queryDesc);
+		ExecutorEnd(queryDesc);
+
+		FreeQueryDesc(queryDesc);
+
+		PopActiveSnapshot();
+	}
+
+	if (is_matview)
+	{
+		/* Roll back any GUC changes */
+		AtEOXact_GUC(false, save_nestlevel);
+
+		/* Restore userid and security context */
+		SetUserIdAndSecContext(save_userid, save_sec_context);
+	}
+
+	return address;
+}
+
+/*
+ * GetIntoRelEFlags --- compute executor flags needed for CREATE TABLE AS
+ *
+ * This is exported because EXPLAIN and PREPARE need it too.  (Note: those
+ * callers still need to deal explicitly with the skipData flag; since they
+ * use different methods for suppressing execution, it doesn't seem worth
+ * trying to encapsulate that part.)
+ */
+int
+GetIntoRelEFlags(IntoClause *intoClause)
+{
+	int			flags = 0;
+
+	if (intoClause->skipData)
+		flags |= EXEC_FLAG_WITH_NO_DATA;
+
+	return flags;
+}
+
+/*
+ * CreateTableAsRelExists --- check existence of relation for CreateTableAsStmt
+ *
+ * Utility wrapper checking if the relation pending for creation in this
+ * CreateTableAsStmt query already exists or not.  Returns true if the
+ * relation exists, otherwise false.
+ */
+bool
+CreateTableAsRelExists(CreateTableAsStmt *ctas)
+{
+	Oid			nspid;
+	Oid			oldrelid;
+	ObjectAddress address;
+	IntoClause *into = ctas->into;
+
+	nspid = RangeVarGetCreationNamespace(into->rel);
+
+	oldrelid = get_relname_relid(into->rel->relname, nspid);
+	if (OidIsValid(oldrelid))
+	{
+		if (!ctas->if_not_exists)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_TABLE),
+					 errmsg("relation \"%s\" already exists",
+							into->rel->relname)));
+
+		/*
+		 * The relation exists and IF NOT EXISTS has been specified.
+		 *
+		 * If we are in an extension script, insist that the pre-existing
+		 * object be a member of the extension, to avoid security risks.
+		 */
+		ObjectAddressSet(address, RelationRelationId, oldrelid);
+		checkMembershipInCurrentExtension(&address);
+
+		/* OK to skip */
+		ereport(NOTICE,
+				(errcode(ERRCODE_DUPLICATE_TABLE),
+				 errmsg("relation \"%s\" already exists, skipping",
+						into->rel->relname)));
+		return true;
+	}
+
+	/* Relation does not exist, it can be created */
+	return false;
+}
+
+/*
+ * CreateIntoRelDestReceiver -- create a suitable DestReceiver object
+ *
+ * intoClause will be NULL if called from CreateDestReceiver(), in which
+ * case it has to be provided later.  However, it is convenient to allow
+ * self->into to be filled in immediately for other callers.
+ */
+DestReceiver *
+CreateIntoRelDestReceiver(IntoClause *intoClause)
+{
+	DR_intorel *self = (DR_intorel *) palloc0(sizeof(DR_intorel));
+
+	self->pub.receiveSlot = intorel_receive;
+	self->pub.rStartup = intorel_startup;
+	self->pub.rShutdown = intorel_shutdown;
+	self->pub.rDestroy = intorel_destroy;
+	self->pub.mydest = DestIntoRel;
+	self->into = intoClause;
+	/* other private fields will be set during intorel_startup */
+
+	return (DestReceiver *) self;
+}
+
+/*
+ * intorel_startup --- executor startup
+ */
+static void
+intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
+{
+	DR_intorel *myState = (DR_intorel *) self;
+	IntoClause *into = myState->into;
+	bool		is_matview;
+	List	   *attrList;
+	ObjectAddress intoRelationAddr;
+	Relation	intoRelationDesc;
+	ListCell   *lc;
+	int			attnum;
+
+	Assert(into != NULL);		/* else somebody forgot to set it */
+
+	/* This code supports both CREATE TABLE AS and CREATE MATERIALIZED VIEW */
+	is_matview = (into->viewQuery != NULL);
+
+	/*
+	 * Build column definitions using "pre-cooked" type and collation info. If
+	 * a column name list was specified in CREATE TABLE AS, override the
+	 * column names derived from the query.  (Too few column names are OK, too
+	 * many are not.)
+	 */
+	attrList = NIL;
+	lc = list_head(into->colNames);
+	for (attnum = 0; attnum < typeinfo->natts; attnum++)
+	{
+		Form_pg_attribute attribute = TupleDescAttr(typeinfo, attnum);
+		ColumnDef  *col;
+		char	   *colname;
+
+		if (lc)
+		{
+			colname = strVal(lfirst(lc));
+			lc = lnext(into->colNames, lc);
+		}
+		else
+			colname = NameStr(attribute->attname);
+
+		col = makeColumnDef(colname,
+							attribute->atttypid,
+							attribute->atttypmod,
+							attribute->attcollation);
+
+		/*
+		 * It's possible that the column is of a collatable type but the
+		 * collation could not be resolved, so double-check.  (We must check
+		 * this here because DefineRelation would adopt the type's default
+		 * collation rather than complaining.)
+		 */
+		if (!OidIsValid(col->collOid) &&
+			type_is_collatable(col->typeName->typeOid))
+			ereport(ERROR,
+					(errcode(ERRCODE_INDETERMINATE_COLLATION),
+					 errmsg("no collation was derived for column \"%s\" with collatable type %s",
+							col->colname,
+							format_type_be(col->typeName->typeOid)),
+					 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+		attrList = lappend(attrList, col);
+	}
+
+	if (lc != NULL)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("too many column names were specified")));
+
+	/*
+	 * Actually create the target table
+	 */
+	intoRelationAddr = create_ctas_internal(attrList, into);
+
+	/*
+	 * Finally we can open the target table
+	 */
+	intoRelationDesc = table_open(intoRelationAddr.objectId, AccessExclusiveLock);
+
+	/*
+	 * Make sure the constructed table does not have RLS enabled.
+	 *
+	 * check_enable_rls() will ereport(ERROR) itself if the user has requested
+	 * something invalid, and otherwise will return RLS_ENABLED if RLS should
+	 * be enabled here.  We don't actually support that currently, so throw
+	 * our own ereport(ERROR) if that happens.
+	 */
+	if (check_enable_rls(intoRelationAddr.objectId, InvalidOid, false) == RLS_ENABLED)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("policies not yet implemented for this command")));
+
+	/*
+	 * Tentatively mark the target as populated, if it's a matview and we're
+	 * going to fill it; otherwise, no change needed.
+	 */
+	if (is_matview && !into->skipData)
+		SetMatViewPopulatedState(intoRelationDesc, true);
+
+	/*
+	 * Fill private fields of myState for use by later routines
+	 */
+	myState->rel = intoRelationDesc;
+	myState->reladdr = intoRelationAddr;
+	myState->output_cid = GetCurrentCommandId(true);
+	myState->ti_options = TABLE_INSERT_SKIP_FSM;
+
+	/*
+	 * If WITH NO DATA is specified, there is no need to set up the state for
+	 * bulk inserts as there are no tuples to insert.
+	 */
+	if (!into->skipData)
+		myState->bistate = GetBulkInsertState();
+	else
+		myState->bistate = NULL;
+
+	/*
+	 * Valid smgr_targblock implies something already wrote to the relation.
+	 * This may be harmless, but this function hasn't planned for it.
+	 */
+	Assert(RelationGetTargetBlock(intoRelationDesc) == InvalidBlockNumber);
+}
+
+/*
+ * intorel_receive --- receive one tuple
+ */
+static bool
+intorel_receive(TupleTableSlot *slot, DestReceiver *self)
+{
+	DR_intorel *myState = (DR_intorel *) self;
+
+	/* Nothing to insert if WITH NO DATA is specified. */
+	if (!myState->into->skipData)
+	{
+		/*
+		 * Note that the input slot might not be of the type of the target
+		 * relation. That's supported by table_tuple_insert(), but slightly
+		 * less efficient than inserting with the right slot - but the
+		 * alternative would be to copy into a slot of the right type, which
+		 * would not be cheap either. This also doesn't allow accessing per-AM
+		 * data (say a tuple's xmin), but since we don't do that here...
+		 */
+		table_tuple_insert(myState->rel,
+						   slot,
+						   myState->output_cid,
+						   myState->ti_options,
+						   myState->bistate);
+	}
+
+	/* We know this is a newly created relation, so there are no indexes */
+
+	return true;
+}
+
+/*
+ * intorel_shutdown --- executor end
+ */
+static void
+intorel_shutdown(DestReceiver *self)
+{
+	DR_intorel *myState = (DR_intorel *) self;
+	IntoClause *into = myState->into;
+
+	if (!into->skipData)
+	{
+		FreeBulkInsertState(myState->bistate);
+		table_finish_bulk_insert(myState->rel, myState->ti_options);
+	}
+
+	/* close rel, but keep lock until commit */
+	table_close(myState->rel, NoLock);
+	myState->rel = NULL;
+}
+
+/*
+ * intorel_destroy --- release DestReceiver object
+ */
+static void
+intorel_destroy(DestReceiver *self)
+{
+	pfree(self);
+}