FahdShalhoub
c3465bedb1
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26 lines
1.4 KiB
SQL
26 lines
1.4 KiB
SQL
-- Lexical search over video titles.
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--
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-- The vector is a generated column rather than something the consumer writes:
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-- the catalogue's only writer is SaveVideo, and a title that arrives in an
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-- announcement should be searchable because it is stored, not because a second
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-- statement remembered to index it. STORED because a GIN index needs the value
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-- on disk to index it at all.
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--
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-- 'arabic' is the text search configuration, not 'english' or 'simple': it
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-- stems Arabic (الوثائقي -> وثايق) while leaving Latin-script tokens as written,
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-- which is the right trade for a mixed catalogue. The cost is that English
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-- words are not stemmed, so "documentaries" does not find "documentary".
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--
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-- The configuration is named explicitly rather than left to default_text_search_config,
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-- which is a per-session GUC — an expression that reads it is only STABLE, and
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-- a generated column requires IMMUTABLE. Naming it is also what keeps the
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-- column and every query in step: a query built with a different
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-- configuration would stem its terms differently and silently match nothing.
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ALTER TABLE videos
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ADD COLUMN search_vector tsvector
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GENERATED ALWAYS AS (to_tsvector('arabic', title)) STORED;
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-- GIN, not GiST: the catalogue is read far more than it is written, and GIN
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-- answers @@ faster at the cost of a slower update — the right way round here.
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CREATE INDEX videos_search_vector_idx ON videos USING GIN (search_vector);
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