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Handle subquery merging with references correctly #8662

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Aug 23, 2021
Merged

Handle subquery merging with references correctly #8662

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16 changes: 9 additions & 7 deletions go/vt/vtgate/planbuilder/route.go
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Original file line number Diff line number Diff line change
Expand Up @@ -458,9 +458,15 @@ func (rb *route) SubqueryCanMerge(pb *primitiveBuilder, inner *route) bool {
if rb.eroute.Keyspace.Name != inner.eroute.Keyspace.Name {
return false
}

// if either side is a reference table, we can just merge it and use the opcode of the other side
if rb.eroute.Opcode == engine.SelectReference || inner.eroute.Opcode == engine.SelectReference {
return true
}

switch rb.eroute.Opcode {
case engine.SelectUnsharded, engine.SelectDBA, engine.SelectReference:
return rb.eroute.Opcode == inner.eroute.Opcode || inner.eroute.Opcode == engine.SelectReference
case engine.SelectUnsharded, engine.SelectDBA:
return rb.eroute.Opcode == inner.eroute.Opcode
case engine.SelectEqualUnique:
// Check if they target the same shard.
if inner.eroute.Opcode == engine.SelectEqualUnique && rb.eroute.Vindex == inner.eroute.Vindex && valEqual(rb.condition, inner.condition) {
Expand All @@ -469,11 +475,7 @@ func (rb *route) SubqueryCanMerge(pb *primitiveBuilder, inner *route) bool {
case engine.SelectNext:
return false
}
// Any sharded plan (including SelectEqualUnique) can merge on a reference table subquery.
// This excludes the case of SelectReference with a sharded subquery.
if inner.eroute.Opcode == engine.SelectReference {
return true
}

switch vals := inner.condition.(type) {
case *sqlparser.ColName:
if pb.st.Vindex(vals, rb) == inner.eroute.Vindex {
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4 changes: 2 additions & 2 deletions go/vt/vtgate/planbuilder/route_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -87,9 +87,9 @@ func TestSubqueryCanMerge(t *testing.T) {
{false, false, false, false, false, false, false, false, true, false},
{false, false, false, false, false, false, false, false, true, false},
{false, false, false, false, false, false, false, false, true, false},
{false, false, false, false, false, false, false, false, false, false},
{false, false, false, false, false, false, false, true, true, false},
{false, false, false, false, false, false, false, false, true, false},
{false, false, false, false, false, false, false, true, true, false},
{true, true, true, true, true, true, true, true, true, true},
{false, false, false, false, false, false, false, false, true, false},
}

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19 changes: 19 additions & 0 deletions go/vt/vtgate/planbuilder/testdata/dml_cases.txt
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Expand Up @@ -2427,3 +2427,22 @@ Gen4 plan same as above
"delete user from (select * from user) music where id = 1"
"Unknown table 'user' in MULTI DELETE"
Gen4 plan same as above

"INSERT INTO main.user_privacy_consents (user_id, accepted_at) SELECT user_id, accepted_at FROM (SELECT 1 as user_id, 1629194864 as accepted_at) AS tmp WHERE NOT EXISTS (SELECT user_id FROM main.user_privacy_consents WHERE user_id = 1)"
{
"QueryType": "INSERT",
"Original": "INSERT INTO main.user_privacy_consents (user_id, accepted_at) SELECT user_id, accepted_at FROM (SELECT 1 as user_id, 1629194864 as accepted_at) AS tmp WHERE NOT EXISTS (SELECT user_id FROM main.user_privacy_consents WHERE user_id = 1)",
"Instructions": {
"OperatorType": "Insert",
"Variant": "Unsharded",
"Keyspace": {
"Name": "main",
"Sharded": false
},
"TargetTabletType": "PRIMARY",
"MultiShardAutocommit": false,
"Query": "insert into user_privacy_consents(user_id, accepted_at) select user_id, accepted_at from (select 1 as user_id, 1629194864 as accepted_at from dual) as tmp where not exists (select user_id from user_privacy_consents where user_id = 1)",
"TableName": "user_privacy_consents"
}
}
Gen4 plan same as above