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71d60e2aa0
This allows a trigger function to determine for an UPDATE trigger which columns were actually updated. This allows some optimizations in generic trigger functions such as lo_manage and tsvector_update_trigger. Reviewed-by: Daniel Gustafsson <daniel@yesql.se> Discussion: https://www.postgresql.org/message-id/flat/11c5f156-67a9-0fb5-8200-2a8018eb2e0c@2ndquadrant.com
31 lines
656 B
SQL
31 lines
656 B
SQL
CREATE EXTENSION lo;
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CREATE TABLE image (title text, raster lo);
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CREATE TRIGGER t_raster BEFORE UPDATE OR DELETE ON image
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FOR EACH ROW EXECUTE PROCEDURE lo_manage(raster);
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SELECT lo_create(43213);
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SELECT lo_create(43214);
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INSERT INTO image (title, raster) VALUES ('beautiful image', 43213);
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SELECT lo_get(43213);
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SELECT lo_get(43214);
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UPDATE image SET raster = 43214 WHERE title = 'beautiful image';
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SELECT lo_get(43213);
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SELECT lo_get(43214);
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-- test updating of unrelated column
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UPDATE image SET title = 'beautiful picture' WHERE title = 'beautiful image';
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SELECT lo_get(43214);
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DELETE FROM image;
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SELECT lo_get(43214);
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DROP TABLE image;
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