DioCrafts
82 lines
2.9 KiB
PL/PgSQL
82 lines
2.9 KiB
PL/PgSQL
\set ON_ERROR_STOP on
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\pset pager off
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\pset format unaligned
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\pset tuples_only on
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-- A/B the post-migration integrity sampler. `ORDER BY random()` assigns and
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-- sorts a random float for every blob. BLAKE3/SHA-style hex hashes are already
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-- uniformly distributed, so a cryptographically random pivot plus an indexed
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-- ordered window yields a rotating sample in O(log N + sample) work.
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BEGIN;
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CREATE TEMP TABLE perf_verify_blobs (
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hash varchar(64) PRIMARY KEY,
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size bigint NOT NULL
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);
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INSERT INTO perf_verify_blobs
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SELECT md5(n::text) || md5((n + 1000003)::text), 262144
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FROM generate_series(1, 1000000) n;
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ANALYZE perf_verify_blobs;
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-- Exact sample-size/equivalence gates for a middle pivot and wraparound pivot.
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SELECT 'middle_count|' || COUNT(*) FROM (
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SELECT hash, size FROM perf_verify_blobs
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WHERE hash >= '8000000000000000000000000000000000000000000000000000000000000000'
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ORDER BY hash LIMIT 100
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) sample;
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WITH tail AS (
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SELECT hash, size FROM perf_verify_blobs
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WHERE hash >= 'fffff000000000000000000000000000000000000000000000000000000000000'
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ORDER BY hash LIMIT 100
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), wrapped AS (
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SELECT * FROM tail
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UNION ALL
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(SELECT hash, size FROM perf_verify_blobs
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WHERE hash < 'fffff000000000000000000000000000000000000000000000000000000000000'
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ORDER BY hash
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LIMIT (100 - (SELECT COUNT(*) FROM tail)))
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)
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SELECT 'wrap_count|' || COUNT(*) FROM wrapped;
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\o /dev/null
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\timing on
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\echo random_warmup
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SELECT hash, size FROM perf_verify_blobs ORDER BY random() LIMIT 100;
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\echo indexed_warmup
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SELECT hash, size FROM perf_verify_blobs
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WHERE hash >= '8000000000000000000000000000000000000000000000000000000000000000'
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ORDER BY hash LIMIT 100;
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\echo random_1
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SELECT hash, size FROM perf_verify_blobs ORDER BY random() LIMIT 100;
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\echo indexed_1
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SELECT hash, size FROM perf_verify_blobs
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WHERE hash >= '8000000000000000000000000000000000000000000000000000000000000000'
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ORDER BY hash LIMIT 100;
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\echo indexed_2
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SELECT hash, size FROM perf_verify_blobs
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WHERE hash >= '4000000000000000000000000000000000000000000000000000000000000000'
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ORDER BY hash LIMIT 100;
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\echo random_2
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SELECT hash, size FROM perf_verify_blobs ORDER BY random() LIMIT 100;
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\echo random_3
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SELECT hash, size FROM perf_verify_blobs ORDER BY random() LIMIT 100;
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\echo indexed_3
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SELECT hash, size FROM perf_verify_blobs
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WHERE hash >= 'c000000000000000000000000000000000000000000000000000000000000000'
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ORDER BY hash LIMIT 100;
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\echo indexed_4
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SELECT hash, size FROM perf_verify_blobs
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WHERE hash >= '2000000000000000000000000000000000000000000000000000000000000000'
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ORDER BY hash LIMIT 100;
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\echo random_4
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SELECT hash, size FROM perf_verify_blobs ORDER BY random() LIMIT 100;
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\echo random_5
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SELECT hash, size FROM perf_verify_blobs ORDER BY random() LIMIT 100;
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\echo indexed_5
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SELECT hash, size FROM perf_verify_blobs
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WHERE hash >= 'e000000000000000000000000000000000000000000000000000000000000000'
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ORDER BY hash LIMIT 100;
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\timing off
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\o
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ROLLBACK;
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