[jkaczman]

Previously, with query_parser set to auto or session_control, we were running the session control regex on all queries to look for SET, BEGIN, COMMIT, etc. This includes queries such as SELECT 1. In the pooler microbench flamegraph (#2035), the check was a pretty substantial amount (see below):

Now, if the query starts with SELECT, INSERT, UPDATE, DELETE or WITH, we return early and skip the expensive regex call.

How can we do this? All of the session control patterns occur at the very start of the query text (when there's no whitespace / comment present); i.e., if we have a query that starts with a keyword like SELECT, which isn't in the CMD_BASE keywords, there's no point in trying to match with CMD_RE.

session_control_and_locks behavior not changed

[codecov]

Codecov Report

❌ Patch coverage is 96.42857% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pgdog/src/frontend/regex_parser.rs	96.42%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

[github-actions]

Metal bench (arm64) passed. All 520 measures within bounds.

suite	throughput	cpu/txn	user cycles/txn	user instr/txn	kernel cycles/txn	kernel instr/txn	ctx/txn
pooler		18.88 (-0.7% ± 1.4%)	17,870 (-1.6% ± 0.9%)	31,391 (-0.6% ± 0.05%)	30,442 (-0.2% ± 2.0%)	51,066 (+0.1% ± 0.3%)
lb		19.54 (-0.4% ± 0.7%)	18,494 (-1.7% ± 0.5%)	32,291 (-0.6% ± 0.1%)	31,327 (+0.7% ± 0.9%)	52,140 (+0.0% ± 0.5%)
sharding-w2		32.15 (-0.5% ± 1.2%)	42,982 (+0.0% ± 1.0%)	94,863 (-0.0% ± 0.02%)	40,326 (-1.2% ± 2.6%)	53,680 (+0.0% ± 0.06%)	1.547 (+0.0% ± 0.2%)
sharding-w8	242,588 (-0.0% ± 0.7%)	29.42 (-0.2% ± 1.2%)	44,389 (-0.3% ± 2.0%)	50,448 (+0.0% ± 0.04%)	36,839 (-0.2% ± 0.5%)	42,390 (+0.0% ± 0.1%)	0.1688 (+1.2% ± 3.7%)

Counters per txn

suite	frontend stall	l1i refill	backend stall
pooler	7,536 (-3.1% ± 2.2%)	2,646 (-1.9% ± 0.8%)
lb	7,932 (-3.7% ± 0.8%)	2,705 (-2.2% ± 0.4%)
sharding-w2	17,437 (+0.2% ± 3.0%)	4,066 (+0.3% ± 1.6%)
sharding-w8	20,331 (+0.7% ± 1.8%)	4,121 (+0.7% ± 1.3%)

Microbench: all 507 measures within bounds.

Hot code per txn

path	base	head	change
pooler	113.0 KB	111.1 KB	-1.9 KB
sharding-w2	167.6 KB	166.7 KB	-0.9 KB

pooler:

crate	base	head	change
pgdog::frontend::client::query_engine	19.9 KB	19.8 KB	-0.1 KB
tokio	18.4 KB	18.3 KB	-0.1 KB
pgdog::backend::pool	17.5 KB	17.6 KB	+0.1 KB
aws-lc (TLS crypto)	10.0 KB	10.1 KB	+0.1 KB
rustls (TLS)	8.3 KB	8.4 KB	+0.1 KB
pgdog::frontend (other)	7.8 KB	7.8 KB	+0.1 KB
pgdog::backend::server	7.8 KB	7.7 KB	-0.1 KB
other	5.8 KB	5.7 KB	-0.1 KB
everything else	17.6 KB	15.8 KB	-1.8 KB

function	head	change
pgdog::frontend::client::Client::run::{{closure}}	5.5 KB	+0.1 KB
pgdog::frontend::client::query_engine::query::<impl pgdog::frontend::client::query_engine:	5.2 KB	-0.1 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	+0.1 KB
tokio::runtime::task::raw::poll	3.1 KB	-0.1 KB

sharding-w2:

crate	base	head	change
pgdog::frontend::router	28.8 KB	28.5 KB	-0.3 KB
pgdog::frontend::client::query_engine	21.1 KB	21.1 KB	-0.1 KB
pgdog::backend::pool	18.4 KB	18.5 KB	+0.1 KB
tokio	19.0 KB	18.4 KB	-0.6 KB
aws-lc (TLS crypto)	12.7 KB	12.2 KB	-0.4 KB
other	10.0 KB	9.8 KB	-0.2 KB
pgdog::frontend (other)	8.8 KB	8.9 KB	+0.1 KB
rustls (TLS)	8.2 KB	8.2 KB	+0.1 KB
everything else	40.6 KB	40.9 KB	+0.4 KB

function	head	change
pgdog::frontend::client::Client::run::{{closure}}	6.4 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}}	4.0 KB	+0.0 KB
pgdog::frontend::router::parser::query::select::<impl pgdog::frontend::router::parser::que	3.2 KB	-0.1 KB
tokio::runtime::task::raw::poll	3.2 KB	-0.3 KB

lb flamegraph vs 5bb8ba3

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Open interactive.

microbench flamegraph vs 5bb8ba3

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Open interactive.

pooler flamegraph vs 5bb8ba3

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Open interactive.

sharding-w2 flamegraph vs 5bb8ba3

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Open interactive.

sharding-w8 flamegraph vs 5bb8ba3

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Open interactive.

Logs

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

Compared 75bc8ac with 5bb8ba3 on c8g.metal-24xl (on-demand).

[github-actions]

Metal bench (x86) passed. All 520 measures within bounds.

suite	throughput	cpu/txn	user cycles/txn	user instr/txn	kernel cycles/txn	kernel instr/txn	ctx/txn
pooler		25.87 (-0.2% ± 0.5%)	18,630 (-0.6% ± 0.3%)	32,703 (-0.6% ± 0.2%)	33,694 (-0.2% ± 1.0%)	36,556 (-0.1% ± 0.3%)
lb		26.27 (-0.1% ± 0.5%)	19,188 (-0.6% ± 0.2%)	33,697 (-0.6% ± 0.04%)	33,839 (+0.1% ± 0.9%)	37,241 (-0.1% ± 0.6%)
sharding-w2		41.94 (+0.0% ± 2.3%)	47,025 (+0.3% ± 1.0%)	98,537 (-0.0% ± 0.08%)	38,442 (-0.3% ± 2.9%)	40,128 (-0.0% ± 0.1%)	1.527 (-0.0% ± 0.3%)
sharding-w8	206,091 (-0.1% ± 1.2%)	32.89 (-0.0% ± 0.9%)	45,919 (-0.1% ± 1.3%)	52,875 (+0.0% ± 0.07%)	31,266 (+0.1% ± 0.8%)	32,513 (-0.0% ± 0.2%)	0.1737 (+0.1% ± 0.9%)

Counters per txn

suite	frontend stall	l1i refill	backend stall
pooler	3,422 (-1.3% ± 0.6%)	1,138 (-1.1% ± 1.2%)	38,275 (-0.5% ± 0.5%)
lb	3,630 (-0.8% ± 0.9%)	1,185 (-0.5% ± 0.7%)	38,733 (-0.6% ± 0.5%)
sharding-w2	6,711 (-0.8% ± 1.7%)	1,540 (-1.4% ± 2.0%)	112,654 (+1.4% ± 3.4%)
sharding-w8	3,617 (-0.7% ± 0.7%)	872 (-2.2% ± 1.2%)	176,660 (-0.1% ± 1.8%)

Microbench: all 507 measures within bounds.

Hot code per txn

path	base	head	change
pooler	114.6 KB	114.2 KB	-0.4 KB
sharding-w2	170.2 KB	168.9 KB	-1.3 KB

pooler:

crate	base	head	change
pgdog::frontend::client::query_engine	22.2 KB	22.4 KB	+0.1 KB
pgdog::backend::pool	18.1 KB	18.4 KB	+0.3 KB
tokio	18.4 KB	18.2 KB	-0.2 KB
pgdog::frontend (other)	9.2 KB	9.2 KB	+0.1 KB
aws-lc (TLS crypto)	8.8 KB	9.1 KB	+0.3 KB
pgdog::backend::server	7.9 KB	7.8 KB	-0.2 KB
rustls (TLS)	7.8 KB	7.7 KB	-0.1 KB
other	5.6 KB	5.8 KB	+0.2 KB
everything else	16.5 KB	15.6 KB	-0.9 KB

function	head	change
pgdog::frontend::client::Client::run::{{closure}}	7.1 KB	-0.1 KB
pgdog::frontend::client::query_engine::query::<impl pgdog::frontend::client::query_engine:	6.8 KB	+0.2 KB
pgdog::frontend::client::query_engine::QueryEngine::handle::{{closure}}	4.6 KB	-0.1 KB
tokio::runtime::task::raw::poll	3.7 KB	+0.1 KB
pgdog::frontend::client::query_engine::query::<impl pgdog::frontend::client::query_engine:	3.6 KB	-0.1 KB

sharding-w2:

crate	base	head	change
pgdog::frontend::router	28.6 KB	28.1 KB	-0.5 KB
pgdog::frontend::client::query_engine	23.2 KB	23.3 KB	+0.1 KB
pgdog::backend::pool	19.2 KB	19.1 KB	-0.1 KB
tokio	18.6 KB	18.5 KB	-0.1 KB
pgdog::frontend (other)	10.8 KB	10.9 KB	+0.1 KB
other	10.6 KB	10.7 KB	+0.1 KB
aws-lc (TLS crypto)	10.6 KB	10.5 KB	-0.1 KB
pgdog::backend::server	8.5 KB	8.4 KB	-0.1 KB
everything else	40.1 KB	39.4 KB	-0.8 KB

function	head	change
pgdog::frontend::client::Client::run::{{closure}}	8.4 KB	+0.1 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}}	4.6 KB	-0.1 KB
tokio::runtime::task::raw::poll	4.1 KB	+0.1 KB
pgdog::frontend::router::parser::query::select::<impl pgdog::frontend::router::parser::que	4.1 KB	-0.1 KB

lb flamegraph vs 5bb8ba3

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Open interactive.

microbench flamegraph vs 5bb8ba3

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Open interactive.

pooler flamegraph vs 5bb8ba3

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Open interactive.

sharding-w2 flamegraph vs 5bb8ba3

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Open interactive.

sharding-w8 flamegraph vs 5bb8ba3

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Open interactive.

Logs

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

Compared 75bc8ac with 5bb8ba3 on c7i.metal-48xl (on-demand).