Merge pull request #5154 from citusdata/col/use-correct-snapshot

pull/5188/head
Onur Tirtir 2021-09-02 11:20:27 +03:00 committed by GitHub
commit 0bf29200eb
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8 changed files with 273 additions and 43 deletions

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@ -88,7 +88,7 @@ static void GetHighestUsedAddressAndId(uint64 storageId,
static List * ReadDataFileStripeList(uint64 storageId, Snapshot snapshot);
static StripeMetadata * BuildStripeMetadata(Datum *datumArray);
static uint32 * ReadChunkGroupRowCounts(uint64 storageId, uint64 stripe, uint32
chunkGroupCount);
chunkGroupCount, Snapshot snapshot);
static Oid ColumnarStorageIdSequenceRelationId(void);
static Oid ColumnarStripeRelationId(void);
static Oid ColumnarStripePKeyIndexRelationId(void);
@ -484,8 +484,6 @@ SaveStripeSkipList(RelFileNode relfilenode, uint64 stripe, StripeSkipList *chunk
FinishModifyRelation(modifyState);
table_close(columnarChunk, RowExclusiveLock);
CommandCounterIncrement();
}
@ -522,8 +520,6 @@ SaveChunkGroups(RelFileNode relfilenode, uint64 stripe,
FinishModifyRelation(modifyState);
table_close(columnarChunkGroup, NoLock);
CommandCounterIncrement();
}
@ -532,7 +528,7 @@ SaveChunkGroups(RelFileNode relfilenode, uint64 stripe,
*/
StripeSkipList *
ReadStripeSkipList(RelFileNode relfilenode, uint64 stripe, TupleDesc tupleDescriptor,
uint32 chunkCount)
uint32 chunkCount, Snapshot snapshot)
{
int32 columnIndex = 0;
HeapTuple heapTuple = NULL;
@ -550,8 +546,8 @@ ReadStripeSkipList(RelFileNode relfilenode, uint64 stripe, TupleDesc tupleDescri
ScanKeyInit(&scanKey[1], Anum_columnar_chunk_stripe,
BTEqualStrategyNumber, F_OIDEQ, Int32GetDatum(stripe));
SysScanDesc scanDescriptor = systable_beginscan_ordered(columnarChunk, index, NULL,
2, scanKey);
SysScanDesc scanDescriptor = systable_beginscan_ordered(columnarChunk, index,
snapshot, 2, scanKey);
StripeSkipList *chunkList = palloc0(sizeof(StripeSkipList));
chunkList->chunkCount = chunkCount;
@ -634,7 +630,7 @@ ReadStripeSkipList(RelFileNode relfilenode, uint64 stripe, TupleDesc tupleDescri
table_close(columnarChunk, AccessShareLock);
chunkList->chunkGroupRowCounts =
ReadChunkGroupRowCounts(storageId, stripe, chunkCount);
ReadChunkGroupRowCounts(storageId, stripe, chunkCount, snapshot);
return chunkList;
}
@ -803,7 +799,8 @@ FindStripeWithHighestRowNumber(Relation relation, Snapshot snapshot)
* given stripe.
*/
static uint32 *
ReadChunkGroupRowCounts(uint64 storageId, uint64 stripe, uint32 chunkGroupCount)
ReadChunkGroupRowCounts(uint64 storageId, uint64 stripe, uint32 chunkGroupCount,
Snapshot snapshot)
{
Oid columnarChunkGroupOid = ColumnarChunkGroupRelationId();
Relation columnarChunkGroup = table_open(columnarChunkGroupOid, AccessShareLock);
@ -816,7 +813,7 @@ ReadChunkGroupRowCounts(uint64 storageId, uint64 stripe, uint32 chunkGroupCount)
BTEqualStrategyNumber, F_OIDEQ, Int32GetDatum(stripe));
SysScanDesc scanDescriptor =
systable_beginscan_ordered(columnarChunkGroup, index, NULL, 2, scanKey);
systable_beginscan_ordered(columnarChunkGroup, index, snapshot, 2, scanKey);
uint32 chunkGroupIndex = 0;
HeapTuple heapTuple = NULL;
@ -886,8 +883,6 @@ InsertStripeMetadataRow(uint64 storageId, StripeMetadata *stripe)
FinishModifyRelation(modifyState);
CommandCounterIncrement();
table_close(columnarStripes, RowExclusiveLock);
}
@ -1205,6 +1200,8 @@ FinishModifyRelation(ModifyState *state)
ExecCleanUpTriggerState(state->estate);
ExecResetTupleTable(state->estate->es_tupleTable, false);
FreeExecutorState(state->estate);
CommandCounterIncrement();
}

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@ -88,6 +88,9 @@ struct ColumnarReadState
* itself.
*/
MemoryContext scanContext;
Snapshot snapshot;
bool snapshotRegisteredByUs;
};
/* static function declarations */
@ -109,7 +112,8 @@ static bool HasUnreadStripe(ColumnarReadState *readState);
static StripeReadState * BeginStripeRead(StripeMetadata *stripeMetadata, Relation rel,
TupleDesc tupleDesc, List *projectedColumnList,
List *whereClauseList, List *whereClauseVars,
MemoryContext stripeReadContext);
MemoryContext stripeReadContext,
Snapshot snapshot);
static void AdvanceStripeRead(ColumnarReadState *readState);
static bool ReadStripeNextRow(StripeReadState *stripeReadState, Datum *columnValues,
bool *columnNulls);
@ -128,7 +132,8 @@ static StripeBuffers * LoadFilteredStripeBuffers(Relation relation,
List *projectedColumnList,
List *whereClauseList,
List *whereClauseVars,
int64 *chunkGroupsFiltered);
int64 *chunkGroupsFiltered,
Snapshot snapshot);
static ColumnBuffers * LoadColumnBuffers(Relation relation,
ColumnChunkSkipNode *chunkSkipNodeArray,
uint32 chunkCount, uint64 stripeOffset,
@ -167,7 +172,8 @@ static Datum ColumnDefaultValue(TupleConstr *tupleConstraints,
ColumnarReadState *
ColumnarBeginRead(Relation relation, TupleDesc tupleDescriptor,
List *projectedColumnList, List *whereClauseList,
MemoryContext scanContext)
MemoryContext scanContext, Snapshot snapshot,
bool snapshotRegisteredByUs)
{
/*
* We allocate all stripe specific data in the stripeReadContext, and reset
@ -187,8 +193,10 @@ ColumnarBeginRead(Relation relation, TupleDesc tupleDescriptor,
readState->stripeReadState = NULL;
readState->currentStripeMetadata = FindNextStripeByRowNumber(relation,
COLUMNAR_INVALID_ROW_NUMBER,
GetTransactionSnapshot());
snapshot);
readState->scanContext = scanContext;
readState->snapshot = snapshot;
readState->snapshotRegisteredByUs = snapshotRegisteredByUs;
return readState;
}
@ -230,7 +238,8 @@ ColumnarReadNextRow(ColumnarReadState *readState, Datum *columnValues, bool *col
readState->projectedColumnList,
readState->whereClauseList,
readState->whereClauseVars,
readState->stripeReadContext);
readState->stripeReadContext,
readState->snapshot);
}
if (!ReadStripeNextRow(readState->stripeReadState, columnValues, columnNulls))
@ -260,11 +269,12 @@ ColumnarReadNextRow(ColumnarReadState *readState, Datum *columnValues, bool *col
bool
ColumnarReadRowByRowNumber(ColumnarReadState *readState,
uint64 rowNumber, Datum *columnValues,
bool *columnNulls, Snapshot snapshot)
bool *columnNulls)
{
if (!ColumnarReadIsCurrentStripe(readState, rowNumber))
{
Relation columnarRelation = readState->relation;
Snapshot snapshot = readState->snapshot;
StripeMetadata *stripeMetadata = FindStripeByRowNumber(columnarRelation,
rowNumber, snapshot);
if (stripeMetadata == NULL)
@ -286,7 +296,8 @@ ColumnarReadRowByRowNumber(ColumnarReadState *readState,
readState->projectedColumnList,
whereClauseList,
whereClauseVars,
stripeReadContext);
stripeReadContext,
snapshot);
readState->currentStripeMetadata = stripeMetadata;
}
@ -446,7 +457,7 @@ ColumnarRescan(ColumnarReadState *readState)
ColumnarResetRead(readState);
readState->currentStripeMetadata = FindNextStripeByRowNumber(readState->relation,
COLUMNAR_INVALID_ROW_NUMBER,
GetTransactionSnapshot());
readState->snapshot);
readState->chunkGroupsFiltered = 0;
MemoryContextSwitchTo(oldContext);
@ -459,6 +470,15 @@ ColumnarRescan(ColumnarReadState *readState)
void
ColumnarEndRead(ColumnarReadState *readState)
{
if (readState->snapshotRegisteredByUs)
{
/*
* init_columnar_read_state created a new snapshot and registered it,
* so now forget it.
*/
UnregisterSnapshot(readState->snapshot);
}
MemoryContextDelete(readState->stripeReadContext);
if (readState->currentStripeMetadata)
{
@ -493,7 +513,7 @@ ColumnarResetRead(ColumnarReadState *readState)
static StripeReadState *
BeginStripeRead(StripeMetadata *stripeMetadata, Relation rel, TupleDesc tupleDesc,
List *projectedColumnList, List *whereClauseList, List *whereClauseVars,
MemoryContext stripeReadContext)
MemoryContext stripeReadContext, Snapshot snapshot)
{
MemoryContext oldContext = MemoryContextSwitchTo(stripeReadContext);
@ -513,7 +533,8 @@ BeginStripeRead(StripeMetadata *stripeMetadata, Relation rel, TupleDesc tupleDes
whereClauseList,
whereClauseVars,
&stripeReadState->
chunkGroupsFiltered);
chunkGroupsFiltered,
snapshot);
stripeReadState->rowCount = stripeReadState->stripeBuffers->rowCount;
@ -540,7 +561,7 @@ AdvanceStripeRead(ColumnarReadState *readState)
StripeGetHighestRowNumber(readState->currentStripeMetadata);
readState->currentStripeMetadata = FindNextStripeByRowNumber(readState->relation,
lastReadRowNumber,
GetTransactionSnapshot());
readState->snapshot);
readState->stripeReadState = NULL;
MemoryContextReset(readState->stripeReadContext);
@ -792,7 +813,7 @@ static StripeBuffers *
LoadFilteredStripeBuffers(Relation relation, StripeMetadata *stripeMetadata,
TupleDesc tupleDescriptor, List *projectedColumnList,
List *whereClauseList, List *whereClauseVars,
int64 *chunkGroupsFiltered)
int64 *chunkGroupsFiltered, Snapshot snapshot)
{
uint32 columnIndex = 0;
uint32 columnCount = tupleDescriptor->natts;
@ -802,7 +823,8 @@ LoadFilteredStripeBuffers(Relation relation, StripeMetadata *stripeMetadata,
StripeSkipList *stripeSkipList = ReadStripeSkipList(relation->rd_node,
stripeMetadata->id,
tupleDescriptor,
stripeMetadata->chunkCount);
stripeMetadata->chunkCount,
snapshot);
bool *selectedChunkMask = SelectedChunkMask(stripeSkipList, whereClauseList,
whereClauseVars, chunkGroupsFiltered);

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@ -227,8 +227,6 @@ columnar_beginscan_extended(Relation relation, Snapshot snapshot,
"cannot read from table when there is unflushed data in upper transactions");
}
FlushWriteStateForRelfilenode(relfilenode, GetCurrentSubTransactionId());
MemoryContextSwitchTo(oldContext);
return ((TableScanDesc) scan);
@ -253,13 +251,56 @@ CreateColumnarScanMemoryContext(void)
*/
static ColumnarReadState *
init_columnar_read_state(Relation relation, TupleDesc tupdesc, Bitmapset *attr_needed,
List *scanQual, MemoryContext scanContext)
List *scanQual, MemoryContext scanContext, Snapshot snapshot)
{
MemoryContext oldContext = MemoryContextSwitchTo(scanContext);
Oid relfilenode = relation->rd_node.relNode;
FlushWriteStateForRelfilenode(relfilenode, GetCurrentSubTransactionId());
bool snapshotRegisteredByUs = false;
if (snapshot != InvalidSnapshot && IsMVCCSnapshot(snapshot))
{
/*
* If we flushed any pending writes, then we should guarantee that
* those writes are visible to us too. For this reason, if given
* snapshot is an MVCC snapshot, then we set its curcid to current
* command id.
*
* For simplicity, we do that even if we didn't flush any writes
* since we don't see any problem with that.
*
* XXX: We should either not update cid if we are executing a FETCH
* (from cursor) command, or we should have a better way to deal with
* pending writes, see the discussion in
* https://github.com/citusdata/citus/issues/5231.
*/
PushCopiedSnapshot(snapshot);
/* now our snapshot is the active one */
UpdateActiveSnapshotCommandId();
snapshot = GetActiveSnapshot();
RegisterSnapshot(snapshot);
/*
* To be able to use UpdateActiveSnapshotCommandId, we pushed the
* copied snapshot to the stack. However, we don't need to keep it
* there since we will anyway rely on ColumnarReadState->snapshot
* during read operation.
*
* Note that since we registered the snapshot already, we guarantee
* that PopActiveSnapshot won't free it.
*/
PopActiveSnapshot();
/* not forget to unregister it when finishing read operation */
snapshotRegisteredByUs = true;
}
List *neededColumnList = NeededColumnsList(tupdesc, attr_needed);
ColumnarReadState *readState = ColumnarBeginRead(relation, tupdesc, neededColumnList,
scanQual, scanContext);
scanQual, scanContext, snapshot,
snapshotRegisteredByUs);
MemoryContextSwitchTo(oldContext);
@ -309,7 +350,7 @@ columnar_getnextslot(TableScanDesc sscan, ScanDirection direction, TupleTableSlo
scan->cs_readState =
init_columnar_read_state(scan->cs_base.rs_rd, slot->tts_tupleDescriptor,
scan->attr_needed, scan->scanQual,
scan->scanContext);
scan->scanContext, scan->cs_base.rs_snapshot);
}
ExecClearTuple(slot);
@ -429,8 +470,6 @@ columnar_index_fetch_begin(Relation rel)
"upper transactions");
}
FlushWriteStateForRelfilenode(relfilenode, GetCurrentSubTransactionId());
MemoryContext scanContext = CreateColumnarScanMemoryContext();
MemoryContext oldContext = MemoryContextSwitchTo(scanContext);
@ -503,12 +542,13 @@ columnar_index_fetch_tuple(struct IndexFetchTableData *sscan,
scan->cs_readState = init_columnar_read_state(columnarRelation,
slot->tts_tupleDescriptor,
attr_needed, scanQual,
scan->scanContext);
scan->scanContext,
snapshot);
}
uint64 rowNumber = tid_to_row_number(*tid);
if (!ColumnarReadRowByRowNumber(scan->cs_readState, rowNumber, slot->tts_values,
slot->tts_isnull, snapshot))
slot->tts_isnull))
{
return false;
}
@ -550,7 +590,9 @@ static bool
columnar_tuple_satisfies_snapshot(Relation rel, TupleTableSlot *slot,
Snapshot snapshot)
{
return true;
uint64 rowNumber = tid_to_row_number(slot->tts_tid);
StripeMetadata *stripeMetadata = FindStripeByRowNumber(rel, rowNumber, snapshot);
return stripeMetadata != NULL;
}
@ -800,10 +842,13 @@ columnar_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
/* no quals for table rewrite */
List *scanQual = NIL;
/* use SnapshotAny when re-writing table as heapAM does */
Snapshot snapshot = SnapshotAny;
MemoryContext scanContext = CreateColumnarScanMemoryContext();
ColumnarReadState *readState = init_columnar_read_state(OldHeap, sourceDesc,
attr_needed, scanQual,
scanContext);
scanContext, snapshot);
Datum *values = palloc0(sourceDesc->natts * sizeof(Datum));
bool *nulls = palloc0(sourceDesc->natts * sizeof(bool));
@ -911,7 +956,8 @@ LogRelationStats(Relation rel, int elevel)
StripeMetadata *stripe = lfirst(stripeMetadataCell);
StripeSkipList *skiplist = ReadStripeSkipList(relfilenode, stripe->id,
RelationGetDescr(rel),
stripe->chunkCount);
stripe->chunkCount,
GetTransactionSnapshot());
for (uint32 column = 0; column < skiplist->columnCount; column++)
{
bool attrDropped = tupdesc->attrs[column].attisdropped;

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@ -213,13 +213,15 @@ extern ColumnarReadState * ColumnarBeginRead(Relation relation,
TupleDesc tupleDescriptor,
List *projectedColumnList,
List *qualConditions,
MemoryContext scanContext);
MemoryContext scanContext,
Snapshot snaphot,
bool snapshotRegisteredByUs);
extern bool ColumnarReadNextRow(ColumnarReadState *state, Datum *columnValues,
bool *columnNulls, uint64 *rowNumber);
extern void ColumnarRescan(ColumnarReadState *readState);
extern bool ColumnarReadRowByRowNumber(ColumnarReadState *readState,
uint64 rowNumber, Datum *columnValues,
bool *columnNulls, Snapshot snapshot);
bool *columnNulls);
extern void ColumnarEndRead(ColumnarReadState *state);
extern void ColumnarResetRead(ColumnarReadState *readState);
extern int64 ColumnarReadChunkGroupsFiltered(ColumnarReadState *state);
@ -255,7 +257,8 @@ extern void SaveChunkGroups(RelFileNode relfilenode, uint64 stripe,
List *chunkGroupRowCounts);
extern StripeSkipList * ReadStripeSkipList(RelFileNode relfilenode, uint64 stripe,
TupleDesc tupleDescriptor,
uint32 chunkCount);
uint32 chunkCount,
Snapshot snapshot);
extern StripeMetadata * FindNextStripeByRowNumber(Relation relation, uint64 rowNumber,
Snapshot snapshot);
extern StripeMetadata * FindStripeByRowNumber(Relation relation, uint64 rowNumber,

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@ -1,6 +1,8 @@
--
-- Testing insert on columnar tables.
--
CREATE SCHEMA columnar_insert;
SET search_path TO columnar_insert;
CREATE TABLE test_insert_command (a int) USING columnar;
-- test single row inserts fail
select count(*) from test_insert_command;
@ -228,4 +230,67 @@ ORDER BY 1,2,3,4;
zero_col | 5 | 0 | 64
(5 rows)
DROP TABLE zero_col;
CREATE TABLE selfinsert(x int) USING columnar;
SELECT alter_columnar_table_set('selfinsert', stripe_row_limit => 1000);
alter_columnar_table_set
---------------------------------------------------------------------
(1 row)
BEGIN;
INSERT INTO selfinsert SELECT generate_series(1,1010);
INSERT INTO selfinsert SELECT * FROM selfinsert;
SELECT SUM(x)=1021110 FROM selfinsert;
?column?
---------------------------------------------------------------------
t
(1 row)
ROLLBACK;
BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
INSERT INTO selfinsert SELECT generate_series(1,1010);
INSERT INTO selfinsert SELECT * FROM selfinsert;
SELECT SUM(x)=1021110 FROM selfinsert;
?column?
---------------------------------------------------------------------
t
(1 row)
ROLLBACK;
INSERT INTO selfinsert SELECT generate_series(1,1010);
INSERT INTO selfinsert SELECT * FROM selfinsert;
SELECT SUM(x)=1021110 FROM selfinsert;
?column?
---------------------------------------------------------------------
t
(1 row)
CREATE TABLE selfconflict (f1 int PRIMARY KEY, f2 int) USING columnar;
BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
INSERT INTO selfconflict VALUES (2,1), (2,2);
ERROR: duplicate key value violates unique constraint "selfconflict_pkey"
DETAIL: Key (f1)=(2) already exists.
COMMIT;
SELECT COUNT(*)=0 FROM selfconflict;
?column?
---------------------------------------------------------------------
t
(1 row)
CREATE TABLE flush_create_index(a int, b int) USING columnar;
BEGIN;
INSERT INTO flush_create_index VALUES (5, 10);
SET enable_seqscan TO OFF;
SET columnar.enable_custom_scan TO OFF;
SET enable_indexscan TO ON;
CREATE INDEX ON flush_create_index(a);
SELECT a FROM flush_create_index WHERE a=5;
a
---------------------------------------------------------------------
5
(1 row)
ROLLBACK;
RESET search_path;
SET client_min_messages TO WARNING;
DROP SCHEMA columnar_insert CASCADE;

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@ -202,3 +202,43 @@ stripe_metadata_for_test_insert_concurrency_ok
t
(1 row)
starting permutation: s1-begin s2-begin-repeatable s1-insert s2-insert s2-select s1-commit s2-select s2-commit
step s1-begin:
BEGIN;
step s2-begin-repeatable:
BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
step s1-insert:
INSERT INTO test_insert_concurrency SELECT i, 2 * i FROM generate_series(1, 3) i;
step s2-insert:
INSERT INTO test_insert_concurrency SELECT i, 2 * i FROM generate_series(4, 6) i;
step s2-select:
SELECT * FROM test_insert_concurrency ORDER BY a;
a| b
---------------------------------------------------------------------
4| 8
5|10
6|12
(3 rows)
step s1-commit:
COMMIT;
step s2-select:
SELECT * FROM test_insert_concurrency ORDER BY a;
a| b
---------------------------------------------------------------------
4| 8
5|10
6|12
(3 rows)
step s2-commit:
COMMIT;

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@ -74,6 +74,11 @@ step "s2-begin"
BEGIN;
}
step "s2-begin-repeatable"
{
BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
}
step "s2-insert"
{
INSERT INTO test_insert_concurrency SELECT i, 2 * i FROM generate_series(4, 6) i;
@ -103,3 +108,5 @@ permutation "s1-begin" "s2-begin" "s2-insert" "s1-copy" "s1-select" "s2-select"
# Then verify that while the stripe written by session 2 has the greater first_row_number, stripe written by session 1 has
# the greater stripe_num. This is because, we reserve stripe_num and first_row_number at different times.
permutation "s1-truncate" "s1-begin" "s1-insert-10000-rows" "s2-begin" "s2-insert" "s2-commit" "s1-commit" "s1-verify-metadata"
permutation "s1-begin" "s2-begin-repeatable" "s1-insert" "s2-insert" "s2-select" "s1-commit" "s2-select" "s2-commit"

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@ -2,6 +2,9 @@
-- Testing insert on columnar tables.
--
CREATE SCHEMA columnar_insert;
SET search_path TO columnar_insert;
CREATE TABLE test_insert_command (a int) USING columnar;
-- test single row inserts fail
@ -152,4 +155,51 @@ SELECT relname, stripe_num, chunk_group_num, row_count FROM columnar.chunk_group
WHERE columnar_test_helpers.columnar_relation_storageid(b.oid)=a.storage_id AND relname = 'zero_col'
ORDER BY 1,2,3,4;
DROP TABLE zero_col;
CREATE TABLE selfinsert(x int) USING columnar;
SELECT alter_columnar_table_set('selfinsert', stripe_row_limit => 1000);
BEGIN;
INSERT INTO selfinsert SELECT generate_series(1,1010);
INSERT INTO selfinsert SELECT * FROM selfinsert;
SELECT SUM(x)=1021110 FROM selfinsert;
ROLLBACK;
BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
INSERT INTO selfinsert SELECT generate_series(1,1010);
INSERT INTO selfinsert SELECT * FROM selfinsert;
SELECT SUM(x)=1021110 FROM selfinsert;
ROLLBACK;
INSERT INTO selfinsert SELECT generate_series(1,1010);
INSERT INTO selfinsert SELECT * FROM selfinsert;
SELECT SUM(x)=1021110 FROM selfinsert;
CREATE TABLE selfconflict (f1 int PRIMARY KEY, f2 int) USING columnar;
BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ;
INSERT INTO selfconflict VALUES (2,1), (2,2);
COMMIT;
SELECT COUNT(*)=0 FROM selfconflict;
CREATE TABLE flush_create_index(a int, b int) USING columnar;
BEGIN;
INSERT INTO flush_create_index VALUES (5, 10);
SET enable_seqscan TO OFF;
SET columnar.enable_custom_scan TO OFF;
SET enable_indexscan TO ON;
CREATE INDEX ON flush_create_index(a);
SELECT a FROM flush_create_index WHERE a=5;
ROLLBACK;
RESET search_path;
SET client_min_messages TO WARNING;
DROP SCHEMA columnar_insert CASCADE;