Thanks Amit for the review comments.
On Sat, Dec 5, 2020 at 4:27 PM Amit Kapila <amit.kapil...@gmail.com> wrote:
>
> > If I'm not wrong, I think currently we have no exec nodes for DDLs.
> > I'm not sure whether we would like to introduce one for this.
>
> Yeah, I am also not in favor of having an executor node for CTAS but
> OTOH, I also don't like the way you have jammed the relevant
> information in generic PlanState. How about keeping it in GatherState
> and initializing it in ExecCreateTableAs() after the executor start.
> You are already doing special treatment for the Gather node in
> ExecCreateTableAs (via IsParallelInsertInCTASAllowed) so we can as
> well initialize the required information in GatherState in
> ExecCreateTableAs. I think that might help in reducing the special
> treatment for intoclause at different places.
>
Done. Added required info to GatherState node. While this reduced the
changes at many other places, but had to pass the into clause and
object id to ExecInitParallelPlan() as we do not send GatherState node
to it. Hope that's okay.
>
> Few other assorted comments:
> =========================
> 1.
> This looks a bit odd. The function name
> 'IsParallelInsertInCTASAllowed' suggests that it just checks whether
> parallelism is allowed but it is internally changing the plan_rows. It
> might be better to do this separately if the parallelism is allowed.
>
Changed.
>
> 2.
> static void ExecShutdownGatherWorkers(GatherState *node);
> -
> +static void ExecParallelInsertInCTAS(GatherState *node);
>
> Spurious line removal.
>
Corrected.
>
> 3.
> The comment and code appear a bit misleading as the function seems to
> shutdown the workers rather than waiting for them to finish. How about
> using something like below:
>
> /*
> * Next, accumulate buffer and WAL usage. (This must wait for the workers
> * to finish, or we might get incomplete data.)
> */
> if (nworkers > 0)
> {
> int i;
>
> /* Wait for all vacuum workers to finish */
> WaitForParallelWorkersToFinish(lps->pcxt);
>
> for (i = 0; i < lps->pcxt->nworkers_launched; i++)
> InstrAccumParallelQuery(&lps->buffer_usage[i], &lps->wal_usage[i]);
> }
>
> This is how it works for parallel vacuum.
>
Done.
>
> 4.
> The above comment doesn't seem to convey what it intends to convey.
> How about changing it slightly as: "We don't compute the
> parallel_tuple_cost for CTAS because the number of tuples that are
> transferred from workers to the gather node is zero as each worker
> parallelly inserts the tuples that are resulted from its chunk of plan
> execution. This change may make the parallel plan cheap among all
> other plans, and influence the planner to consider this parallel
> plan."
>
Changed.
>
> Then, we can also have an Assert for path->path.rows to zero for the CTAS
> case.
>
We can not have Assert(path->path.rows == 0), because we are not
changing this parameter upstream in or before the planning phase. We
are just skipping to take it into account for CTAS. We may have to do
extra checks over different places in case we have to make planner
path->path.rows to 0 for CTAS. IMHO, that's not necessary. We can just
skip taking this value in cost_gather. Thoughts?
>
> 5.
> + /* Prallel inserts in CTAS related info is specified below. */
> + IntoClause *intoclause;
> + Oid objectid;
> + DestReceiver *dest;
> } PlanState;
>
> Typo. /Prallel/Parallel
>
Corrected.
>
> 6.
> Currently, it seems the plan look like:
> Gather (actual time=970.524..972.913 rows=0 loops=1)
> -> Create t1_test
> Workers Planned: 2
> Workers Launched: 2
> -> Parallel Seq Scan on t1 (actual time=0.028..86.623 rows=333333
> loops=3)
>
> I would prefer it to be:
> Gather (actual time=970.524..972.913 rows=0 loops=1)
> Workers Planned: 2
> Workers Launched: 2
> -> Create t1_test
> -> Parallel Seq Scan on t1 (actual time=0.028..86.623 rows=333333
> loops=3)
>
> This way it looks like the writing part is done below the Gather node
> and also it will match the Parallel Insert patch of Greg.
>
Done.
Attaching v7 patch. Please review it further.
With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com
From 7eff47d971c0ac5722ddc7de5a4c7e7550bb71aa Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddy@enterprisedb.com>
Date: Sun, 6 Dec 2020 08:21:42 +0530
Subject: [PATCH v7] Parallel Inserts in CREATE TABLE AS
The idea of this patch is to allow the leader and each worker
insert the tuples in parallel if the SELECT part of the CTAS is
parallelizable.
The design:
Let the planner know that the SELECT is from CTAS in createas.c
so that it can set the number of tuples transferred from the
workers to Gather node to 0. With this change, there are chances
that the planner may choose the parallel plan. After the planning,
check if the upper plan node is Gather in createas.c and mark a
parallelism flag in the CTAS dest receiver. Pass the into clause,
object id, command id from the leader to workers, so that each
worker can create its own CTAS dest receiver. Leader inserts its
share of tuples if instructed to do, and so are workers. Each
worker writes atomically its number of inserted tuples into a
shared memory variable, the leader combines this with its own
number of inserted tuples and shares to the client.
---
src/backend/access/heap/heapam.c | 11 -
src/backend/access/transam/xact.c | 30 +-
src/backend/commands/createas.c | 341 +++++++++++++------
src/backend/commands/explain.c | 41 +++
src/backend/executor/execParallel.c | 70 +++-
src/backend/executor/nodeGather.c | 114 ++++++-
src/backend/executor/nodeGatherMerge.c | 4 +-
src/backend/optimizer/path/costsize.c | 13 +-
src/include/access/xact.h | 1 +
src/include/commands/createas.h | 28 ++
src/include/executor/execParallel.h | 6 +-
src/include/nodes/execnodes.h | 3 +
src/include/nodes/parsenodes.h | 1 +
src/test/regress/expected/write_parallel.out | 190 +++++++++++
src/test/regress/sql/write_parallel.sql | 84 +++++
15 files changed, 796 insertions(+), 141 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 1b2f70499e..3045c0f046 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2043,17 +2043,6 @@ static HeapTuple
heap_prepare_insert(Relation relation, HeapTuple tup, TransactionId xid,
CommandId cid, int options)
{
- /*
- * To allow parallel inserts, we need to ensure that they are safe to be
- * performed in workers. We have the infrastructure to allow parallel
- * inserts in general except for the cases where inserts generate a new
- * CommandId (eg. inserts into a table having a foreign key column).
- */
- if (IsParallelWorker())
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_TRANSACTION_STATE),
- errmsg("cannot insert tuples in a parallel worker")));
-
tup->t_data->t_infomask &= ~(HEAP_XACT_MASK);
tup->t_data->t_infomask2 &= ~(HEAP2_XACT_MASK);
tup->t_data->t_infomask |= HEAP_XMAX_INVALID;
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 9cd0b7c11b..db6eedd635 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -763,18 +763,34 @@ GetCurrentCommandId(bool used)
/* this is global to a transaction, not subtransaction-local */
if (used)
{
- /*
- * Forbid setting currentCommandIdUsed in a parallel worker, because
- * we have no provision for communicating this back to the leader. We
- * could relax this restriction when currentCommandIdUsed was already
- * true at the start of the parallel operation.
- */
- Assert(!IsParallelWorker());
+ /*
+ * This is a temporary hack for all common parallel insert cases i.e.
+ * insert into, ctas, copy from. To be changed later. In a parallel
+ * worker, set currentCommandIdUsed to true only if it was not set to
+ * true at the start of the parallel operation (by way of
+ * SetCurrentCommandIdUsedForWorker()). We have to do this because
+ * GetCurrentCommandId(true) may be called from anywhere, especially
+ * for parallel inserts, within parallel worker.
+ */
+ Assert(!(IsParallelWorker() && !currentCommandIdUsed));
currentCommandIdUsed = true;
}
return currentCommandId;
}
+/*
+ * SetCurrentCommandIdUsedForWorker
+ *
+ * For a parallel worker, record that the currentCommandId has been used. This
+ * must only be called at the start of a parallel operation.
+ */
+void
+SetCurrentCommandIdUsedForWorker(void)
+{
+ Assert(IsParallelWorker() && !currentCommandIdUsed && currentCommandId != InvalidCommandId);
+ currentCommandIdUsed = true;
+}
+
/*
* SetParallelStartTimestamps
*
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 6bf6c5a310..5d546464dc 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -51,18 +51,6 @@
#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);
@@ -328,6 +316,15 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
query = linitial_node(Query, rewritten);
Assert(query->commandType == CMD_SELECT);
+ /*
+ * Flag to let the planner know that the SELECT query is for CTAS. This
+ * is used to calculate the tuple transfer cost from workers to gather
+ * node(in case parallelism kicks in for the SELECT part of the CTAS),
+ * to zero as each worker will insert its share of tuples in parallel.
+ */
+ if (IsParallelInsertInCTASAllowed(into, NULL))
+ query->isForCTAS = true;
+
/* plan the query */
plan = pg_plan_query(query, pstate->p_sourcetext,
CURSOR_OPT_PARALLEL_OK, params);
@@ -350,6 +347,15 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
/* call ExecutorStart to prepare the plan for execution */
ExecutorStart(queryDesc, GetIntoRelEFlags(into));
+ /*
+ * If SELECT part of the CTAS is parallelizable, then make each
+ * parallel worker insert the tuples that are resulted in its execution
+ * into the target table. We need plan state to be initialized by the
+ * executor to decide whether to allow parallel inserts or not.
+ */
+ if (IsParallelInsertInCTASAllowed(into, queryDesc))
+ SetCTASParallelInsertState(queryDesc);
+
/* run the plan to completion */
ExecutorRun(queryDesc, ForwardScanDirection, 0L, true);
@@ -418,6 +424,9 @@ CreateIntoRelDestReceiver(IntoClause *intoClause)
self->pub.rDestroy = intorel_destroy;
self->pub.mydest = DestIntoRel;
self->into = intoClause;
+ self->is_parallel = false;
+ self->is_parallel_worker = false;
+ self->object_id = InvalidOid;
/* other private fields will be set during intorel_startup */
return (DestReceiver *) self;
@@ -430,121 +439,169 @@ 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);
+ if (myState->is_parallel_worker)
+ {
+ /* In the worker */
+ intoRelationDesc = table_open(myState->object_id, AccessExclusiveLock);
+ myState->rel = intoRelationDesc;
+ myState->reladdr = InvalidObjectAddress;
+ myState->ti_options = 0;
+ myState->bistate = GetBulkInsertState();
- /*
- * 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++)
+ /*
+ * Right after the table is created in the leader, the command id is
+ * incremented (in create_ctas_internal()). The new command id is
+ * marked as used in intorel_startup(), then the parallel mode is
+ * entered. The command id and transaction id are serialized into
+ * parallel DSM, they are then available to all parallel workers. All
+ * the workers need to mark the command id as used before insertion.
+ */
+ (void) SetCurrentCommandIdUsedForWorker();
+ myState->output_cid = GetCurrentCommandId(false);
+ }
+ else
{
- Form_pg_attribute attribute = TupleDescAttr(typeinfo, attnum);
- ColumnDef *col;
- char *colname;
+ IntoClause *into = myState->into;
+ bool is_matview;
+ List *attrList;
+ 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);
- if (lc)
+ /*
+ * 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++)
{
- colname = strVal(lfirst(lc));
- lc = lnext(into->colNames, lc);
+ 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);
}
- else
- colname = NameStr(attribute->attname);
- col = makeColumnDef(colname,
- attribute->atttypid,
- attribute->atttypmod,
- attribute->attcollation);
+ if (lc != NULL)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("too many column names were specified")));
/*
- * 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.)
+ * Actually create the target table
*/
- 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.")));
+ intoRelationAddr = create_ctas_internal(attrList, into);
- attrList = lappend(attrList, col);
- }
+ /*
+ * Finally we can open the target table
+ */
+ intoRelationDesc = table_open(intoRelationAddr.objectId, AccessExclusiveLock);
- if (lc != NULL)
- ereport(ERROR,
- (errcode(ERRCODE_SYNTAX_ERROR),
- errmsg("too many column names were specified")));
+ /*
+ * 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")));
- /*
- * Actually create the target table
- */
- intoRelationAddr = create_ctas_internal(attrList, into);
+ /*
+ * 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);
- /*
- * Finally we can open the target table
- */
- intoRelationDesc = table_open(intoRelationAddr.objectId, AccessExclusiveLock);
+ /*
+ * 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;
- /*
- * 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")));
+ /*
+ * 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;
- /*
- * 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);
+ if (myState->is_parallel)
+ {
+ myState->object_id = intoRelationAddr.objectId;
- /*
- * 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;
+ /*
+ * We don't need to skip contacting FSM while inserting tuples
+ * for parallel mode, while extending the relations, workers
+ * instead of blocking on a page while another worker is inserting,
+ * can check the FSM for another page that can accommodate the
+ * tuples. This results in major benefit for parallel inserts.
+ */
+ myState->ti_options = 0;
- /*
- * 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;
+ /*
+ * rd_createSubid is marked invalid, otherwise, the table is
+ * not allowed to extend by the workers.
+ */
+ myState->rel->rd_createSubid = InvalidSubTransactionId;
+ }
- /*
- * 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);
+ /*
+ * 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);
+ }
}
/*
@@ -606,3 +663,75 @@ intorel_destroy(DestReceiver *self)
{
pfree(self);
}
+
+/*
+ * IsParallelInsertInCTASAllowed --- determine whether or not parallel
+ * insertion is possible.
+ */
+bool IsParallelInsertInCTASAllowed(IntoClause *into, QueryDesc *queryDesc)
+{
+ bool allowed = false;
+
+ if (IS_CTAS(into))
+ {
+ RangeVar *rel = into->rel;
+
+ /* Allow parallel inserts only if the table is not temporary. */
+ if (rel && rel->relpersistence != RELPERSISTENCE_TEMP)
+ allowed = true;
+
+ if (queryDesc && allowed)
+ {
+ PlanState *ps = queryDesc->planstate;
+ PlannedStmt *plannedstmt = queryDesc->plannedstmt;
+
+ /*
+ * We allow parallel inserts by the workers only if the Gather node
+ * has no projections to perform and if the upper node is Gather.
+ * In case, the Gather node has projections, which is possible if
+ * there are any subplans in the query, the workers can not do
+ * those projections. And when the upper node is GatherMerge, then
+ * the leader has to perform the final phase i.e. merge the results
+ * by workers.
+ */
+ if (!(ps && IsA(ps, GatherState) && !ps->ps_ProjInfo &&
+ plannedstmt->parallelModeNeeded &&
+ plannedstmt->planTree &&
+ IsA(plannedstmt->planTree, Gather) &&
+ plannedstmt->planTree->lefttree &&
+ plannedstmt->planTree->lefttree->parallel_aware &&
+ plannedstmt->planTree->lefttree->parallel_safe))
+ {
+ allowed = false;
+ }
+ }
+ }
+
+ return allowed;
+}
+
+/*
+ * SetCTASParallelInsertState --- set the required info for the parallel
+ * inserts, that is required in the plan exection.
+ */
+void SetCTASParallelInsertState(QueryDesc *queryDesc)
+{
+ GatherState *gstate = (GatherState *) queryDesc->planstate;
+
+ /*
+ * For parallelizing inserts in CTAS i.e. making each parallel worker
+ * insert the tuples, we must send information such as intoclause(for
+ * eachworker to build separate dest receiver), object id(for each worker
+ * to open the created table).
+ */
+ ((DR_intorel *) queryDesc->dest)->is_parallel = true;
+ gstate->dest = queryDesc->dest;
+
+ /*
+ * Since there are no rows that are transferred from workers to Gather
+ * node, so we set it to 0 to be visible in explain plans. Note that we
+ * would have already accounted this for cost calculations in
+ * cost_gather().
+ */
+ queryDesc->plannedstmt->planTree->plan_rows = 0;
+}
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 43f9b01e83..57875e1505 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -371,6 +371,15 @@ ExplainOneQuery(Query *query, int cursorOptions,
return;
}
+ /*
+ * Flag to let the planner know that the SELECT query is for CTAS. This is
+ * used to calculate the tuple transfer cost from workers to gather node(in
+ * case parallelism kicks in for the SELECT part of the CTAS), to zero as
+ * each worker will insert its share of tuples in parallel.
+ */
+ if (IsParallelInsertInCTASAllowed(into, NULL))
+ query->isForCTAS = true;
+
/* if an advisor plugin is present, let it manage things */
if (ExplainOneQuery_hook)
(*ExplainOneQuery_hook) (query, cursorOptions, into, es,
@@ -556,6 +565,15 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
/* call ExecutorStart to prepare the plan for execution */
ExecutorStart(queryDesc, eflags);
+ /*
+ * If SELECT part of the CTAS is parallelizable, then make each parallel
+ * worker insert the tuples that are resulted in its execution into the
+ * target table. We need plan state to be initialized by the executor to
+ * decide whether to allow parallel inserts or not.
+ */
+ if (IsParallelInsertInCTASAllowed(into, queryDesc))
+ SetCTASParallelInsertState(queryDesc);
+
/* Execute the plan for statistics if asked for */
if (es->analyze)
{
@@ -1775,6 +1793,29 @@ ExplainNode(PlanState *planstate, List *ancestors,
if (gather->single_copy || es->format != EXPLAIN_FORMAT_TEXT)
ExplainPropertyBool("Single Copy", gather->single_copy, es);
+
+ /*
+ * Show the create table information under Gather node in case
+ * parallel workers have inserted the rows.
+ */
+ if (IsA(planstate, GatherState))
+ {
+ GatherState *gstate = (GatherState *) planstate;
+
+ if (IS_PARALLEL_CTAS_DEST(gstate->dest) &&
+ ((DR_intorel *) gstate->dest)->into->rel &&
+ ((DR_intorel *) gstate->dest)->into->rel->relname)
+ {
+ es->indent--;
+ ExplainIndentText(es);
+ appendStringInfoString(es->str, "-> ");
+ appendStringInfoString(es->str, "Create ");
+ appendStringInfo(es->str, "%s\n",
+ ((DR_intorel *) gstate->dest)->into->rel->relname);
+ ExplainIndentText(es);
+ es->indent++;
+ }
+ }
}
break;
case T_GatherMerge:
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index befde52691..330978d018 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -23,6 +23,7 @@
#include "postgres.h"
+#include "commands/createas.h"
#include "executor/execParallel.h"
#include "executor/executor.h"
#include "executor/nodeAgg.h"
@@ -65,6 +66,7 @@
#define PARALLEL_KEY_QUERY_TEXT UINT64CONST(0xE000000000000008)
#define PARALLEL_KEY_JIT_INSTRUMENTATION UINT64CONST(0xE000000000000009)
#define PARALLEL_KEY_WAL_USAGE UINT64CONST(0xE00000000000000A)
+#define PARALLEL_KEY_INTO_CLAUSE UINT64CONST(0xE00000000000000B)
#define PARALLEL_TUPLE_QUEUE_SIZE 65536
@@ -77,6 +79,9 @@ typedef struct FixedParallelExecutorState
dsa_pointer param_exec;
int eflags;
int jit_flags;
+ Oid objectid; /* workers to open relation/table. */
+ /* Number tuples inserted by all the workers. */
+ pg_atomic_uint64 processed;
} FixedParallelExecutorState;
/*
@@ -578,7 +583,8 @@ ExecParallelSetupTupleQueues(ParallelContext *pcxt, bool reinitialize)
ParallelExecutorInfo *
ExecInitParallelPlan(PlanState *planstate, EState *estate,
Bitmapset *sendParams, int nworkers,
- int64 tuples_needed)
+ int64 tuples_needed, IntoClause *intoclause,
+ Oid objectid)
{
ParallelExecutorInfo *pei;
ParallelContext *pcxt;
@@ -600,6 +606,8 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate,
Size dsa_minsize = dsa_minimum_size();
char *query_string;
int query_len;
+ char *intoclausestr = NULL;
+ int intoclause_len = 0;
/*
* Force any initplan outputs that we're going to pass to workers to be
@@ -712,6 +720,15 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate,
shm_toc_estimate_chunk(&pcxt->estimator, dsa_minsize);
shm_toc_estimate_keys(&pcxt->estimator, 1);
+ /* Estimate space for into clause for CTAS. */
+ if (IS_CTAS(intoclause) && OidIsValid(objectid))
+ {
+ intoclausestr = nodeToString(intoclause);
+ intoclause_len = strlen(intoclausestr);
+ shm_toc_estimate_chunk(&pcxt->estimator, intoclause_len + 1);
+ shm_toc_estimate_keys(&pcxt->estimator, 1);
+ }
+
/* Everyone's had a chance to ask for space, so now create the DSM. */
InitializeParallelDSM(pcxt);
@@ -729,6 +746,14 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate,
fpes->param_exec = InvalidDsaPointer;
fpes->eflags = estate->es_top_eflags;
fpes->jit_flags = estate->es_jit_flags;
+ pg_atomic_init_u64(&fpes->processed, 0);
+ pei->processed = &fpes->processed;
+
+ if (intoclausestr && OidIsValid(objectid))
+ fpes->objectid = objectid;
+ else
+ fpes->objectid = InvalidOid;
+
shm_toc_insert(pcxt->toc, PARALLEL_KEY_EXECUTOR_FIXED, fpes);
/* Store query string */
@@ -758,8 +783,18 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate,
shm_toc_insert(pcxt->toc, PARALLEL_KEY_WAL_USAGE, walusage_space);
pei->wal_usage = walusage_space;
- /* Set up the tuple queues that the workers will write into. */
- pei->tqueue = ExecParallelSetupTupleQueues(pcxt, false);
+ if (intoclausestr)
+ {
+ char *intoclause_space = shm_toc_allocate(pcxt->toc,
+ intoclause_len + 1);
+ memcpy(intoclause_space, intoclausestr, intoclause_len + 1);
+ shm_toc_insert(pcxt->toc, PARALLEL_KEY_INTO_CLAUSE, intoclause_space);
+ }
+ else
+ {
+ /* Set up the tuple queues that the workers will write into. */
+ pei->tqueue = ExecParallelSetupTupleQueues(pcxt, false);
+ }
/* We don't need the TupleQueueReaders yet, though. */
pei->reader = NULL;
@@ -1387,12 +1422,30 @@ ParallelQueryMain(dsm_segment *seg, shm_toc *toc)
void *area_space;
dsa_area *area;
ParallelWorkerContext pwcxt;
+ char *intoclausestr = NULL;
+ IntoClause *intoclause = NULL;
/* Get fixed-size state. */
fpes = shm_toc_lookup(toc, PARALLEL_KEY_EXECUTOR_FIXED, false);
- /* Set up DestReceiver, SharedExecutorInstrumentation, and QueryDesc. */
- receiver = ExecParallelGetReceiver(seg, toc);
+ intoclausestr = shm_toc_lookup(toc, PARALLEL_KEY_INTO_CLAUSE, true);
+ if (intoclausestr)
+ {
+ /*
+ * If the worker is for parallel insert in CTAS, then use the proper
+ * dest receiver.
+ */
+ intoclause = (IntoClause *) stringToNode(intoclausestr);
+ receiver = CreateIntoRelDestReceiver(intoclause);
+ ((DR_intorel *)receiver)->is_parallel_worker = true;
+ ((DR_intorel *)receiver)->object_id = fpes->objectid;
+ }
+ else
+ {
+ /* Set up DestReceiver, SharedExecutorInstrumentation, and QueryDesc. */
+ receiver = ExecParallelGetReceiver(seg, toc);
+ }
+
instrumentation = shm_toc_lookup(toc, PARALLEL_KEY_INSTRUMENTATION, true);
if (instrumentation != NULL)
instrument_options = instrumentation->instrument_options;
@@ -1471,6 +1524,13 @@ ParallelQueryMain(dsm_segment *seg, shm_toc *toc)
queryDesc->estate->es_jit->instr;
}
+ /*
+ * Write out the number of tuples this worker has inserted. Leader will use
+ * it to inform to the end client.
+ */
+ if (intoclausestr)
+ pg_atomic_add_fetch_u64(&fpes->processed, queryDesc->estate->es_processed);
+
/* Must do this after capturing instrumentation. */
ExecutorEnd(queryDesc);
diff --git a/src/backend/executor/nodeGather.c b/src/backend/executor/nodeGather.c
index a01b46af14..9cef6bdd61 100644
--- a/src/backend/executor/nodeGather.c
+++ b/src/backend/executor/nodeGather.c
@@ -32,6 +32,7 @@
#include "access/relscan.h"
#include "access/xact.h"
+#include "commands/createas.h"
#include "executor/execdebug.h"
#include "executor/execParallel.h"
#include "executor/nodeGather.h"
@@ -48,6 +49,7 @@ static TupleTableSlot *ExecGather(PlanState *pstate);
static TupleTableSlot *gather_getnext(GatherState *gatherstate);
static MinimalTuple gather_readnext(GatherState *gatherstate);
static void ExecShutdownGatherWorkers(GatherState *node);
+static void ExecParallelInsertInCTAS(GatherState *node);
/* ----------------------------------------------------------------
@@ -131,6 +133,73 @@ ExecInitGather(Gather *node, EState *estate, int eflags)
return gatherstate;
}
+/* ----------------------------------------------------------------
+ * ExecParallelInsertInCTAS(node)
+ *
+ * Facilitates parallel inserts by parallel workers and/or
+ * leader for Create Table AS.
+ * ----------------------------------------------------------------
+ */
+static void
+ExecParallelInsertInCTAS(GatherState *node)
+{
+ /* Enable leader to insert in case no parallel workers were launched. */
+ if (node->nworkers_launched == 0)
+ node->need_to_scan_locally = true;
+
+ /*
+ * By now, for parallel workers (if launched any), would have started their
+ * work i.e. insertion to target table. In case the leader is chosen to
+ * participate for parallel inserts in CTAS, then finish its share before
+ * going to wait for the parallel workers to finish.
+ */
+ if (node->need_to_scan_locally)
+ {
+ EState *estate = node->ps.state;
+ TupleTableSlot *outerTupleSlot;
+
+ for(;;)
+ {
+ /* Install our DSA area while executing the plan. */
+ estate->es_query_dsa =
+ node->pei ? node->pei->area : NULL;
+
+ outerTupleSlot = ExecProcNode(node->ps.lefttree);
+
+ estate->es_query_dsa = NULL;
+
+ if(TupIsNull(outerTupleSlot))
+ break;
+
+ (void) node->dest->receiveSlot(outerTupleSlot, node->dest);
+
+ node->ps.state->es_processed++;
+ }
+
+ node->need_to_scan_locally = false;
+ }
+
+ if (node->nworkers_launched > 0)
+ {
+ int i;
+
+ /* Wait for the parallel workers to finish. */
+ WaitForParallelWorkersToFinish(node->pei->pcxt);
+
+ for (i = 0; i < node->nworkers_launched; i++)
+ {
+ InstrAccumParallelQuery(&node->pei->buffer_usage[i],
+ &node->pei->wal_usage[i]);
+ }
+
+ /*
+ * Add up the total tuples inserted by all workers, to the tuples
+ * inserted by the leader(if any). This will be shared to client.
+ */
+ node->ps.state->es_processed += pg_atomic_read_u64(node->pei->processed);
+ }
+}
+
/* ----------------------------------------------------------------
* ExecGather(node)
*
@@ -157,6 +226,7 @@ ExecGather(PlanState *pstate)
{
EState *estate = node->ps.state;
Gather *gather = (Gather *) node->ps.plan;
+ bool isctas = IS_PARALLEL_CTAS_DEST(node->dest);
/*
* Sometimes we might have to run without parallelism; but if parallel
@@ -165,6 +235,18 @@ ExecGather(PlanState *pstate)
if (gather->num_workers > 0 && estate->es_use_parallel_mode)
{
ParallelContext *pcxt;
+ IntoClause *intoclause = NULL;
+ Oid objectid = InvalidOid;
+
+ /*
+ * Take the necessary information to be passed to workers for
+ * parallel inserts in CTAS.
+ */
+ if (isctas)
+ {
+ intoclause = ((DR_intorel *) node->dest)->into;
+ objectid = ((DR_intorel *) node->dest)->object_id;
+ }
/* Initialize, or re-initialize, shared state needed by workers. */
if (!node->pei)
@@ -172,7 +254,10 @@ ExecGather(PlanState *pstate)
estate,
gather->initParam,
gather->num_workers,
- node->tuples_needed);
+ node->tuples_needed,
+ /* CTAS info */
+ intoclause,
+ objectid);
else
ExecParallelReinitialize(node->ps.lefttree,
node->pei,
@@ -190,13 +275,16 @@ ExecGather(PlanState *pstate)
/* Set up tuple queue readers to read the results. */
if (pcxt->nworkers_launched > 0)
{
- ExecParallelCreateReaders(node->pei);
- /* Make a working array showing the active readers */
- node->nreaders = pcxt->nworkers_launched;
- node->reader = (TupleQueueReader **)
- palloc(node->nreaders * sizeof(TupleQueueReader *));
- memcpy(node->reader, node->pei->reader,
- node->nreaders * sizeof(TupleQueueReader *));
+ if (!isctas)
+ {
+ ExecParallelCreateReaders(node->pei);
+ /* Make a working array showing the active readers */
+ node->nreaders = pcxt->nworkers_launched;
+ node->reader = (TupleQueueReader **)
+ palloc(node->nreaders * sizeof(TupleQueueReader *));
+ memcpy(node->reader, node->pei->reader,
+ node->nreaders * sizeof(TupleQueueReader *));
+ }
}
else
{
@@ -208,9 +296,17 @@ ExecGather(PlanState *pstate)
}
/* Run plan locally if no workers or enabled and not single-copy. */
- node->need_to_scan_locally = (node->nreaders == 0)
+ node->need_to_scan_locally = (node->nreaders == 0 &&
+ !isctas)
|| (!gather->single_copy && parallel_leader_participation);
node->initialized = true;
+
+ /* Perform parallel inserts for CTAS. */
+ if (isctas)
+ {
+ ExecParallelInsertInCTAS(node);
+ return NULL;
+ }
}
/*
diff --git a/src/backend/executor/nodeGatherMerge.c b/src/backend/executor/nodeGatherMerge.c
index 47129344f3..ee45272c17 100644
--- a/src/backend/executor/nodeGatherMerge.c
+++ b/src/backend/executor/nodeGatherMerge.c
@@ -216,7 +216,9 @@ ExecGatherMerge(PlanState *pstate)
estate,
gm->initParam,
gm->num_workers,
- node->tuples_needed);
+ node->tuples_needed,
+ NULL,
+ InvalidOid);
else
ExecParallelReinitialize(node->ps.lefttree,
node->pei,
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 22d6935824..225f3cbf01 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -393,7 +393,18 @@ cost_gather(GatherPath *path, PlannerInfo *root,
/* Parallel setup and communication cost. */
startup_cost += parallel_setup_cost;
- run_cost += parallel_tuple_cost * path->path.rows;
+
+ /*
+ * We do not compute the parallel_tuple_cost for CTAS because the number of
+ * tuples that are transferred from workers to the gather node is zero as
+ * each worker, in parallel, inserts the tuples that are resulted from its
+ * chunk of plan execution. This change may make the parallel plan cheap
+ * among all other plans, and influence the planner to consider this
+ * parallel plan.
+ */
+ if (!(root->parse->isForCTAS &&
+ root->query_level == 1))
+ run_cost += parallel_tuple_cost * path->path.rows;
path->path.startup_cost = startup_cost;
path->path.total_cost = (startup_cost + run_cost);
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 7320de345c..5beae6c617 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -389,6 +389,7 @@ extern FullTransactionId GetCurrentFullTransactionIdIfAny(void);
extern void MarkCurrentTransactionIdLoggedIfAny(void);
extern bool SubTransactionIsActive(SubTransactionId subxid);
extern CommandId GetCurrentCommandId(bool used);
+extern void SetCurrentCommandIdUsedForWorker(void);
extern void SetParallelStartTimestamps(TimestampTz xact_ts, TimestampTz stmt_ts);
extern TimestampTz GetCurrentTransactionStartTimestamp(void);
extern TimestampTz GetCurrentStatementStartTimestamp(void);
diff --git a/src/include/commands/createas.h b/src/include/commands/createas.h
index 7629230254..ab3aab58c5 100644
--- a/src/include/commands/createas.h
+++ b/src/include/commands/createas.h
@@ -14,12 +14,35 @@
#ifndef CREATEAS_H
#define CREATEAS_H
+#include "access/heapam.h"
#include "catalog/objectaddress.h"
+#include "executor/execdesc.h"
#include "nodes/params.h"
+#include "nodes/plannodes.h"
#include "parser/parse_node.h"
#include "tcop/dest.h"
#include "utils/queryenvironment.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 */
+ bool is_parallel; /* is parallelism to be considered? */
+ bool is_parallel_worker; /* true for parallel worker */
+ /* Used for table open by parallel worker. */
+ Oid object_id;
+} DR_intorel;
+
+#define IS_CTAS(intoclause) (intoclause && IsA(intoclause, IntoClause))
+#define IS_PARALLEL_CTAS_DEST(dest) (dest && dest->mydest == DestIntoRel && \
+ IS_CTAS(((DR_intorel *) dest)->into) && \
+ ((DR_intorel *) dest)->is_parallel)
extern ObjectAddress ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
ParamListInfo params, QueryEnvironment *queryEnv,
@@ -29,4 +52,9 @@ extern int GetIntoRelEFlags(IntoClause *intoClause);
extern DestReceiver *CreateIntoRelDestReceiver(IntoClause *intoClause);
+extern bool IsParallelInsertInCTASAllowed(IntoClause *into,
+ QueryDesc *queryDesc);
+
+extern void SetCTASParallelInsertState(QueryDesc *queryDesc);
+
#endif /* CREATEAS_H */
diff --git a/src/include/executor/execParallel.h b/src/include/executor/execParallel.h
index 5a39a5b29c..9f959f741b 100644
--- a/src/include/executor/execParallel.h
+++ b/src/include/executor/execParallel.h
@@ -35,11 +35,15 @@ typedef struct ParallelExecutorInfo
/* These two arrays have pcxt->nworkers_launched entries: */
shm_mq_handle **tqueue; /* tuple queues for worker output */
struct TupleQueueReader **reader; /* tuple reader/writer support */
+ /* Number of tuples inserted by all workers. */
+ volatile pg_atomic_uint64 *processed;
} ParallelExecutorInfo;
extern ParallelExecutorInfo *ExecInitParallelPlan(PlanState *planstate,
EState *estate, Bitmapset *sendParam, int nworkers,
- int64 tuples_needed);
+ int64 tuples_needed,
+ IntoClause *intoclause,
+ Oid objectid);
extern void ExecParallelCreateReaders(ParallelExecutorInfo *pei);
extern void ExecParallelFinish(ParallelExecutorInfo *pei);
extern void ExecParallelCleanup(ParallelExecutorInfo *pei);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 61ba4c3666..e9c4442c22 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -23,6 +23,7 @@
#include "nodes/tidbitmap.h"
#include "partitioning/partdefs.h"
#include "storage/condition_variable.h"
+#include "tcop/dest.h"
#include "utils/hsearch.h"
#include "utils/queryenvironment.h"
#include "utils/reltrigger.h"
@@ -2326,6 +2327,8 @@ typedef struct GatherState
int nreaders; /* number of still-active workers */
int nextreader; /* next one to try to read from */
struct TupleQueueReader **reader; /* array with nreaders active entries */
+ /* Parallel inserts in CTAS related info is specified below. */
+ DestReceiver *dest;
} GatherState;
/* ----------------
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index ec14fc2036..eb267b1a6c 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -180,6 +180,7 @@ typedef struct Query
*/
int stmt_location; /* start location, or -1 if unknown */
int stmt_len; /* length in bytes; 0 means "rest of string" */
+ bool isForCTAS; /* is the SELECT query for CREATE TABLE AS */
} Query;
diff --git a/src/test/regress/expected/write_parallel.out b/src/test/regress/expected/write_parallel.out
index 0c4da2591a..635d24e76d 100644
--- a/src/test/regress/expected/write_parallel.out
+++ b/src/test/regress/expected/write_parallel.out
@@ -75,5 +75,195 @@ explain (costs off) create table parallel_write as execute prep_stmt;
(7 rows)
create table parallel_write as execute prep_stmt;
+drop table parallel_write;
+--
+-- Test parallel inserts in create table as/select into/create materialized
+-- view.
+--
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select length(stringu1) from tenk1;
+ QUERY PLAN
+-------------------------------------------------------------
+ Gather (actual rows=0 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Create parallel_write
+ -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
+(5 rows)
+
+drop table parallel_write;
+-- parallel inserts must not occur as the table is temporary
+explain (costs off, analyze on, timing off, summary off)
+create temporary table parallel_write as select length(stringu1) from tenk1;
+ QUERY PLAN
+-------------------------------------------------------------
+ Gather (actual rows=10000 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
+(4 rows)
+
+drop table parallel_write;
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+create unlogged table parallel_write as select length(stringu1) from tenk1;
+ QUERY PLAN
+-------------------------------------------------------------
+ Gather (actual rows=0 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Create parallel_write
+ -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
+(5 rows)
+
+drop table parallel_write;
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+select length(stringu1) into parallel_write from tenk1;
+ QUERY PLAN
+-------------------------------------------------------------
+ Gather (actual rows=0 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Create parallel_write
+ -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
+(5 rows)
+
+drop table parallel_write;
+-- parallel inserts must not occur as the table is temporary
+explain (costs off, analyze on, timing off, summary off)
+select length(stringu1) into temporary parallel_write from tenk1;
+ QUERY PLAN
+-------------------------------------------------------------
+ Gather (actual rows=10000 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
+(4 rows)
+
+drop table parallel_write;
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+select length(stringu1) into unlogged parallel_write from tenk1;
+ QUERY PLAN
+-------------------------------------------------------------
+ Gather (actual rows=0 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Create parallel_write
+ -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
+(5 rows)
+
+drop table parallel_write;
+-- parallel inserts must not occur as the parallelism will not be picked
+-- for select part because of for update clause
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select length(stringu1) from tenk1 for update;
+ QUERY PLAN
+-----------------------------------------------------
+ LockRows (actual rows=10000 loops=1)
+ -> Seq Scan on tenk1 (actual rows=10000 loops=1)
+(2 rows)
+
+drop table parallel_write;
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+create materialized view parallel_mat_view as
+select length(stringu1) from tenk1;
+ QUERY PLAN
+-------------------------------------------------------------
+ Gather (actual rows=0 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Create parallel_mat_view
+ -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
+(5 rows)
+
+drop materialized view parallel_mat_view;
+-- parallel inserts must occur
+prepare parallel_write_prep as select length(stringu1) from tenk1;
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as execute parallel_write_prep;
+ QUERY PLAN
+-------------------------------------------------------------
+ Gather (actual rows=0 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Create parallel_write
+ -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
+(5 rows)
+
+deallocate parallel_write_prep;
+drop table parallel_write;
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select now(), four from tenk1;
+ QUERY PLAN
+-------------------------------------------------------------
+ Gather (actual rows=0 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Create parallel_write
+ -> Parallel Seq Scan on tenk1 (actual rows=2000 loops=5)
+(5 rows)
+
+drop table parallel_write;
+-- parallel inserts must not occur as the parallelism will not be picked
+-- for select part because of the parallel unsafe function
+create sequence parallel_write_sequence;
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as
+select nextval('parallel_write_sequence'), four from tenk1;
+ QUERY PLAN
+-----------------------------------------------
+ Seq Scan on tenk1 (actual rows=10000 loops=1)
+(1 row)
+
+drop table parallel_write;
+drop sequence parallel_write_sequence;
+-- parallel inserts must occur, as there is init plan that gets executed by
+-- each parallel worker
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select two col1,
+ (select two from (select * from tenk2) as tt limit 1) col2
+ from tenk1 where tenk1.four = 3;
+ QUERY PLAN
+------------------------------------------------------------------------
+ Gather (actual rows=0 loops=1)
+ Workers Planned: 4
+ Params Evaluated: $1
+ Workers Launched: 3
+ -> Create parallel_write
+ InitPlan 1 (returns $1)
+ -> Limit (actual rows=1 loops=1)
+ -> Gather (actual rows=1 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Parallel Seq Scan on tenk2 (actual rows=1 loops=5)
+ -> Parallel Seq Scan on tenk1 (actual rows=625 loops=4)
+ Filter: (four = 3)
+ Rows Removed by Filter: 1875
+(14 rows)
+
+drop table parallel_write;
+-- parallel inserts must not occur, as there is sub plan that gets executed by
+-- the Gather node in leader
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select two col1,
+ (select tenk1.two from generate_series(1,1)) col2
+ from tenk1 where tenk1.four = 3;
+ QUERY PLAN
+---------------------------------------------------------------------
+ Gather (actual rows=2500 loops=1)
+ Workers Planned: 4
+ Workers Launched: 4
+ -> Parallel Seq Scan on tenk1 (actual rows=500 loops=5)
+ Filter: (four = 3)
+ Rows Removed by Filter: 1500
+ SubPlan 1
+ -> Function Scan on generate_series (actual rows=1 loops=2500)
+(8 rows)
+
drop table parallel_write;
rollback;
diff --git a/src/test/regress/sql/write_parallel.sql b/src/test/regress/sql/write_parallel.sql
index 78b479cedf..e65a56b442 100644
--- a/src/test/regress/sql/write_parallel.sql
+++ b/src/test/regress/sql/write_parallel.sql
@@ -39,4 +39,88 @@ explain (costs off) create table parallel_write as execute prep_stmt;
create table parallel_write as execute prep_stmt;
drop table parallel_write;
+--
+-- Test parallel inserts in create table as/select into/create materialized
+-- view.
+--
+
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select length(stringu1) from tenk1;
+drop table parallel_write;
+
+-- parallel inserts must not occur as the table is temporary
+explain (costs off, analyze on, timing off, summary off)
+create temporary table parallel_write as select length(stringu1) from tenk1;
+drop table parallel_write;
+
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+create unlogged table parallel_write as select length(stringu1) from tenk1;
+drop table parallel_write;
+
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+select length(stringu1) into parallel_write from tenk1;
+drop table parallel_write;
+
+-- parallel inserts must not occur as the table is temporary
+explain (costs off, analyze on, timing off, summary off)
+select length(stringu1) into temporary parallel_write from tenk1;
+drop table parallel_write;
+
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+select length(stringu1) into unlogged parallel_write from tenk1;
+drop table parallel_write;
+
+-- parallel inserts must not occur as the parallelism will not be picked
+-- for select part because of for update clause
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select length(stringu1) from tenk1 for update;
+drop table parallel_write;
+
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+create materialized view parallel_mat_view as
+select length(stringu1) from tenk1;
+drop materialized view parallel_mat_view;
+
+-- parallel inserts must occur
+prepare parallel_write_prep as select length(stringu1) from tenk1;
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as execute parallel_write_prep;
+deallocate parallel_write_prep;
+drop table parallel_write;
+
+-- parallel inserts must occur
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select now(), four from tenk1;
+drop table parallel_write;
+
+-- parallel inserts must not occur as the parallelism will not be picked
+-- for select part because of the parallel unsafe function
+create sequence parallel_write_sequence;
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as
+select nextval('parallel_write_sequence'), four from tenk1;
+drop table parallel_write;
+drop sequence parallel_write_sequence;
+
+-- parallel inserts must occur, as there is init plan that gets executed by
+-- each parallel worker
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select two col1,
+ (select two from (select * from tenk2) as tt limit 1) col2
+ from tenk1 where tenk1.four = 3;
+drop table parallel_write;
+
+-- parallel inserts must not occur, as there is sub plan that gets executed by
+-- the Gather node in leader
+explain (costs off, analyze on, timing off, summary off)
+create table parallel_write as select two col1,
+ (select tenk1.two from generate_series(1,1)) col2
+ from tenk1 where tenk1.four = 3;
+drop table parallel_write;
+
rollback;
--
2.25.1
