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Use CTAS approach for rebalancing the materialized view #2249

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Merged
whitehawk merged 2 commits into from
Feb 24, 2026
Merged

Use CTAS approach for rebalancing the materialized view #2249

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37dc7e7
Use CTAS approach for rebalancing the materialized view
whitehawk Feb 19, 2026
6766ff0
Update solution
whitehawk Feb 24, 2026
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28 changes: 19 additions & 9 deletions src/backend/commands/tablecmds.c
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Original file line number Diff line number Diff line change
Expand Up @@ -513,7 +513,9 @@ static void ATExecRebalanceTable(List **wqueue, Relation rel, AlterTableCmd *cmd

static void ATRepackTable(Relation origTable, AlteredTableInfo *tab);
static void ATExecExpandPartitionTablePrepare(Relation rel);
static void ATExecExpandTableCTAS(AlterTableCmd *rootCmd, Relation rel, AlterTableCmd *cmd);
static void ATExecRebalanceTableCTAS(AlterTableCmd *rootCmd,
Relation rel, AlterTableCmd *cmd,
int targetNumSegments);

static void ATExecSetDistributedBy(Relation rel, Node *node,
AlterTableCmd *cmd);
Expand Down Expand Up @@ -17513,7 +17515,7 @@ ATExecExpandTable(List **wqueue, Relation rel, AlterTableCmd *cmd)
}
else
{
ATExecExpandTableCTAS(rootCmd, rel, cmd);
ATExecRebalanceTableCTAS(rootCmd, rel, cmd, getgpsegmentCount());
}

/* Update numsegments to cluster size */
Expand Down Expand Up @@ -17651,11 +17653,6 @@ ATExecRebalanceTable(List **wqueue, Relation rel, AlterTableCmd *cmd)
* child partitions.
*/
}
else if (rel->rd_rel->relkind == RELKIND_MATVIEW)
{
ereport((Gp_role == GP_ROLE_EXECUTE) ? DEBUG1 : NOTICE,
(errmsg("Materialized view requires REFRESH after rebalance")));
}
else if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
{
if (rel_is_external_table(relid))
Expand All @@ -17677,6 +17674,18 @@ ATExecRebalanceTable(List **wqueue, Relation rel, AlterTableCmd *cmd)
return;
}
}
else if (rel->rd_rel->relkind == RELKIND_MATVIEW)
{
/*
* We can't insert data directly to an existing matview,
* therefore the approach from ATExecShrinkTable() is not suitable,
* and we use CTAS method for matviews.
*/
AlteredTableInfo *tab = linitial(*wqueue);
AlterTableCmd *rootCmd =
(AlterTableCmd *)linitial(tab->subcmds[AT_PASS_MISC]);
ATExecRebalanceTableCTAS(rootCmd, rel, cmd, targetNumSegments);
}
else
{
ATExecShrinkTable(rel, newPolicy);
Expand Down Expand Up @@ -17778,7 +17787,8 @@ ATExecExpandPartitionTablePrepare(Relation rel)
}

static void
ATExecExpandTableCTAS(AlterTableCmd *rootCmd, Relation rel, AlterTableCmd *cmd)
ATExecRebalanceTableCTAS(AlterTableCmd *rootCmd, Relation rel,
AlterTableCmd *cmd, int targetNumSegments)
{
RangeVar *tmprv;
Oid tmprelid;
Expand Down Expand Up @@ -17817,7 +17827,7 @@ ATExecExpandTableCTAS(AlterTableCmd *rootCmd, Relation rel, AlterTableCmd *cmd)

/* Step (b) - build CTAS */
distby = make_distributedby_for_rel(rel);
distby->numsegments = getgpsegmentCount();
distby->numsegments = targetNumSegments;

queryDesc = build_ctas_with_dist(rel, distby,
untransformRelOptions(get_rel_opts(rel)),
Expand Down
4 changes: 0 additions & 4 deletions src/test/regress/expected/alter_rebalance.out
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Expand Up @@ -3561,8 +3561,6 @@ insert into test_table select generate_series(1, 10);
create materialized view mv_test_table as select a from test_table distributed by (a);
alter table test_table rebalance 1;
alter materialized view mv_test_table rebalance 1;
NOTICE: Materialized view requires REFRESH after rebalance
refresh materialized view mv_test_table;
select count(1), gp_segment_id from test_table group by gp_segment_id;
count | gp_segment_id
-------+---------------
Expand Down Expand Up @@ -3600,8 +3598,6 @@ select count(1), gp_segment_id from mv_test_table group by gp_segment_id order b
begin;
alter table test_table rebalance 1;
alter materialized view mv_test_table rebalance 1;
NOTICE: Materialized view requires REFRESH after rebalance
refresh materialized view mv_test_table;
rollback;
select count(1), gp_segment_id from test_table group by gp_segment_id order by gp_segment_id;
count | gp_segment_id
Expand Down
2 changes: 0 additions & 2 deletions src/test/regress/sql/alter_rebalance.sql
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Expand Up @@ -463,7 +463,6 @@ create materialized view mv_test_table as select a from test_table distributed b

alter table test_table rebalance 1;
alter materialized view mv_test_table rebalance 1;
refresh materialized view mv_test_table;

select count(1), gp_segment_id from test_table group by gp_segment_id;
select count(1), gp_segment_id from mv_test_table group by gp_segment_id;
Expand All @@ -483,7 +482,6 @@ select count(1), gp_segment_id from mv_test_table group by gp_segment_id order b
begin;
alter table test_table rebalance 1;
alter materialized view mv_test_table rebalance 1;
refresh materialized view mv_test_table;
rollback;

select count(1), gp_segment_id from test_table group by gp_segment_id order by gp_segment_id;
Expand Down
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