[jkaczman]

Previously, when we rewrote cross-shard subqueries in WHERE with the rows that those specific subqueries returned, we weren't checking which subquery we replaced, which caused all of the subqueries in WHERE to be replaced with these rows (even for other subqueries we weren't supposed to rewrite, causing incorrect response to be returned)

E.g., if we have a statement such as

SELECT * FROM users WHERE id IN (SELECT user_id FROM orders) AND state IN (SELECT state FROM states)

The subquery is executed and rewritten for the orders subquery, however, it shouldn't be for the states one, as orders is sharded and states isn't. However, previously, both subqueries would be replaced with the user ids from the orders query.

Now, the subquery is matched by location in the statement, so only applicable subqueries are rewritten in this scenario.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[github-actions]

Metal bench (arm64) passed. All 517 measures within bounds.

suite	throughput	cpu/txn	user cycles/txn	user instr/txn	kernel cycles/txn	kernel instr/txn	ctx/txn
pooler		19.15 (+0.6% ± 1.5%)	18,404 (+0.4% ± 0.5%)	31,598 (+0.0% ± 0.04%)	30,648 (+0.9% ± 2.6%)	50,956 (-0.1% ± 0.4%)
lb		19.86 (+0.6% ± 1.1%)	18,990 (+0.3% ± 0.7%)	32,495 (-0.0% ± 0.05%)	31,727 (+0.8% ± 1.7%)	52,103 (-0.1% ± 0.4%)
sharding-w2		31.8 (-0.4% ± 2.6%)	42,951 (-0.5% ± 2.8%)	94,867 (-0.0% ± 0.01%)	39,762 (-0.1% ± 2.5%)	53,707 (-0.0% ± 0.09%)	1.547 (-0.1% ± 0.4%)
sharding-w8	245,618 (+0.3% ± 2.0%)	29.06 (-0.3% ± 2.1%)	44,000 (+0.3% ± 0.2%)	50,448 (-0.0% ± 0.02%)	36,249 (-0.9% ± 4.6%)	42,375 (+0.0% ± 0.2%)	0.1701 (-0.1% ± 3.8%)

Counters per txn

suite	frontend stall	l1i refill	backend stall
pooler	8,078 (+1.2% ± 1.4%)	2,734 (+0.3% ± 0.5%)
lb	8,421 (+0.9% ± 1.9%)	2,785 (+0.3% ± 0.8%)
sharding-w2	17,265 (-1.1% ± 4.8%)	4,066 (-0.7% ± 2.7%)
sharding-w8	19,872 (+1.5% ± 2.5%)	4,094 (+1.2% ± 2.3%)

Microbench: all 504 measures within bounds.

Hot code per txn

path	base	head	change
pooler	113.6 KB	114.0 KB	+0.4 KB
sharding-w2	167.8 KB	170.8 KB	+3.0 KB

pooler:

crate	base	head	change
pgdog::frontend::client::query_engine	19.8 KB	20.0 KB	+0.2 KB
tokio	18.6 KB	18.4 KB	-0.2 KB
pgdog::backend::pool	17.6 KB	17.5 KB	-0.1 KB
aws-lc (TLS crypto)	9.9 KB	10.1 KB	+0.2 KB
rustls (TLS)	8.5 KB	8.4 KB	-0.1 KB
pgdog::frontend (other)	7.8 KB	7.9 KB	+0.2 KB
pgdog::backend::server	7.8 KB	7.8 KB	+0.1 KB
other	6.1 KB	6.1 KB	+0.0 KB
everything else	17.8 KB	17.8 KB	+0.0 KB

function	head	change
pgdog::frontend::client::Client::run::{{closure}}	5.6 KB	+0.1 KB
pgdog::frontend::client::query_engine::query::<impl pgdog::frontend::client::query_engine:	5.2 KB	+0.0 KB
pgdog::frontend::client::query_engine::QueryEngine::handle::{{closure}}	4.3 KB	+0.1 KB
pgdog::frontend::client::query_engine::query::<impl pgdog::frontend::client::query_engine:	3.2 KB	+0.0 KB
tokio::runtime::task::raw::poll	3.1 KB	-0.2 KB

sharding-w2:

crate	base	head	change
pgdog::frontend::router	28.8 KB	29.5 KB	+0.7 KB
pgdog::frontend::client::query_engine	21.0 KB	21.3 KB	+0.3 KB
tokio	19.2 KB	19.4 KB	+0.2 KB
pgdog::backend::pool	18.0 KB	18.8 KB	+0.8 KB
aws-lc (TLS crypto)	12.6 KB	12.8 KB	+0.1 KB
other	10.4 KB	10.1 KB	-0.2 KB
pgdog::frontend (other)	8.9 KB	9.1 KB	+0.1 KB
rustls (TLS)	8.1 KB	8.3 KB	+0.2 KB
everything else	40.8 KB	41.5 KB	+0.8 KB

function	head	change
pgdog::frontend::client::Client::run::{{closure}}	6.5 KB	+0.0 KB
pgdog::frontend::client::query_engine::query::<impl pgdog::frontend::client::query_engine:	5.1 KB	+0.1 KB
pgdog::frontend::client::query_engine::QueryEngine::handle::{{closure}}	4.2 KB	+0.1 KB
tokio::runtime::task::raw::poll	3.6 KB	+0.2 KB
pgdog::frontend::router::parser::query::select::<impl pgdog::frontend::router::parser::que	3.2 KB	-0.1 KB

lb flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

microbench flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

pooler flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

sharding-w2 flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

sharding-w8 flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

Logs

lb, microbench, pooler, sharding-w2, sharding-w8, verdict.json

Compared 64128b5 with 2131844 on c8g.metal-24xl (spot).

[github-actions]

Metal bench (x86) passed. All 517 measures within bounds.

suite	throughput	cpu/txn	user cycles/txn	user instr/txn	kernel cycles/txn	kernel instr/txn	ctx/txn
pooler		25.95 (-0.1% ± 0.3%)	19,016 (-0.1% ± 0.2%)	32,933 (-0.0% ± 0.07%)	33,408 (-0.2% ± 0.3%)	36,422 (-0.3% ± 0.5%)
lb		26.41 (-0.0% ± 0.3%)	19,577 (+0.0% ± 0.2%)	33,912 (+0.0% ± 0.06%)	33,613 (+0.0% ± 0.6%)	37,328 (+0.4% ± 0.5%)
sharding-w2		41.77 (+0.0% ± 1.7%)	46,755 (-0.3% ± 0.7%)	98,577 (+0.0% ± 0.08%)	38,198 (+0.2% ± 3.6%)	40,236 (+0.0% ± 0.1%)	1.53 (+0.1% ± 0.6%)
sharding-w8	207,205 (-0.0% ± 0.3%)	32.75 (+0.1% ± 0.10%)	45,721 (+0.2% ± 0.2%)	52,876 (-0.0% ± 0.02%)	31,121 (-0.0% ± 0.3%)	32,530 (+0.0% ± 0.09%)	0.1736 (-0.5% ± 0.7%)

Counters per txn

suite	frontend stall	l1i refill	backend stall
pooler	3,932 (-0.2% ± 0.6%)	1,214 (+0.1% ± 0.7%)	36,788 (-0.1% ± 0.4%)
lb	4,104 (+0.1% ± 0.7%)	1,250 (+0.1% ± 0.8%)	37,595 (+0.1% ± 0.7%)
sharding-w2	6,325 (-0.5% ± 0.3%)	1,534 (+0.1% ± 0.5%)	113,866 (-0.3% ± 1.7%)
sharding-w8	3,234 (-0.0% ± 1.4%)	863 (+0.3% ± 1.8%)	177,902 (+0.3% ± 0.3%)

Microbench: all 504 measures within bounds.

Hot code per txn

path	base	head	change
pooler	114.8 KB	114.4 KB	-0.3 KB
sharding-w2	167.2 KB	168.0 KB	+0.8 KB

pooler:

crate	base	head	change
pgdog::frontend::client::query_engine	22.2 KB	22.2 KB	+0.0 KB
tokio	18.2 KB	18.4 KB	+0.2 KB
pgdog::backend::pool	17.9 KB	18.2 KB	+0.2 KB
pgdog::frontend (other)	9.2 KB	9.2 KB	+0.0 KB
aws-lc (TLS crypto)	9.0 KB	8.2 KB	-0.8 KB
pgdog::backend::server	8.0 KB	7.9 KB	-0.1 KB
rustls (TLS)	7.9 KB	7.9 KB	+0.1 KB
other	5.7 KB	5.9 KB	+0.2 KB
everything else	16.6 KB	16.5 KB	-0.1 KB

function	head	change
pgdog::frontend::client::Client::run::{{closure}}	7.1 KB	+0.0 KB
pgdog::frontend::client::query_engine::query::<impl pgdog::frontend::client::query_engine:	6.4 KB	+0.0 KB
pgdog::frontend::client::query_engine::QueryEngine::handle::{{closure}}	4.9 KB	-0.1 KB
pgdog::frontend::client::query_engine::query::<impl pgdog::frontend::client::query_engine:	3.8 KB	+0.1 KB
tokio::runtime::task::raw::poll	3.6 KB	-0.1 KB

sharding-w2:

crate	base	head	change
pgdog::frontend::router	28.0 KB	28.1 KB	+0.1 KB
pgdog::frontend::client::query_engine	23.0 KB	23.3 KB	+0.3 KB
pgdog::backend::pool	19.1 KB	18.8 KB	-0.4 KB
tokio	18.3 KB	18.8 KB	+0.4 KB
pgdog::frontend (other)	10.8 KB	10.6 KB	-0.2 KB
aws-lc (TLS crypto)	10.0 KB	10.3 KB	+0.3 KB
other	10.2 KB	10.1 KB	-0.1 KB
pgdog::backend::server	8.6 KB	8.5 KB	-0.1 KB
everything else	39.2 KB	39.6 KB	+0.4 KB

function	head	change
pgdog::frontend::client::Client::run::{{closure}}	8.2 KB	-0.1 KB
pgdog::frontend::client::query_engine::query::<impl pgdog::frontend::client::query_engine:	6.5 KB	+0.2 KB
pgdog::frontend::client::query_engine::QueryEngine::handle::{{closure}}	4.5 KB	-0.1 KB
pgdog::frontend::router::parser::query::select::<impl pgdog::frontend::router::parser::que	4.2 KB	+0.1 KB
tokio::runtime::task::raw::poll	3.9 KB	+0.0 KB

lb flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

microbench flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

pooler flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

sharding-w2 flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

sharding-w8 flamegraph vs 2131844

Open interactive for hover, zoom and search.

Open interactive.

Logs

lb, microbench, pooler, sharding-w2, sharding-w8, verdict.json

Compared 64128b5 with 2131844 on m7i.metal-48xl (spot).