69 lines
2.5 KiB
MySQL
69 lines
2.5 KiB
MySQL
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CREATE OR REPLACE FUNCTION unique_short_id()
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RETURNS TRIGGER AS $$
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-- Declare the variables we'll be using.
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DECLARE
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key TEXT;
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qry TEXT;
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found TEXT;
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BEGIN
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-- generate the first part of a query as a string with safely
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-- escaped table name, using || to concat the parts
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qry := 'SELECT short_id FROM ' || quote_ident(TG_TABLE_NAME) || ' WHERE short_id=';
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-- This loop will probably only run once per call until we've generated
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-- millions of ids.
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LOOP
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-- Generate our string bytes and re-encode as a base64 string.
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key := encode(gen_random_bytes(6), 'base64');
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-- Base64 encoding contains 2 URL unsafe characters by default.
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-- The URL-safe version has these replacements.
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key := replace(key, '/', '_'); -- url safe replacement
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key := replace(key, '+', '-'); -- url safe replacement
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-- Concat the generated key (safely quoted) with the generated query
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-- and run it.
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-- SELECT id FROM "test" WHERE id='blahblah' INTO found
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-- Now "found" will be the duplicated id or NULL.
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EXECUTE qry || quote_literal(key) INTO found;
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-- Check to see if found is NULL.
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-- If we checked to see if found = NULL it would always be FALSE
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-- because (NULL = NULL) is always FALSE.
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IF found IS NULL THEN
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-- If we didn't find a collision then leave the LOOP.
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EXIT;
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END IF;
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-- We haven't EXITed yet, so return to the top of the LOOP
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-- and try again.
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END LOOP;
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-- NEW and OLD are available in TRIGGER PROCEDURES.
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-- NEW is the mutated row that will actually be INSERTed.
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-- We're replacing id, regardless of what it was before
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-- with our key variable.
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NEW.short_id = key;
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-- The RECORD returned here is what will actually be INSERTed,
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-- or what the next trigger will get if there is one.
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RETURN NEW;
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END;
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$$ language 'plpgsql';
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ALTER TABLE project ADD COLUMN short_id text UNIQUE;
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UPDATE project SET short_id = encode(gen_random_bytes(6), 'base64');
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ALTER TABLE project ALTER COLUMN short_id SET NOT NULL;
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ALTER TABLE project ADD CONSTRAINT project_short_id_unique UNIQUE (short_id);
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CREATE TRIGGER trigger_project_short_id BEFORE INSERT ON project FOR EACH ROW EXECUTE PROCEDURE unique_short_id();
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ALTER TABLE task ADD COLUMN short_id text UNIQUE;
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UPDATE task SET short_id = encode(gen_random_bytes(6), 'base64');
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ALTER TABLE task ALTER COLUMN short_id SET NOT NULL;
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ALTER TABLE task ADD CONSTRAINT task_short_id_unique UNIQUE (short_id);
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CREATE TRIGGER trigger_task_short_id BEFORE INSERT ON task FOR EACH ROW EXECUTE PROCEDURE unique_short_id();
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