Carlos Sierra's Tools and Tips

Doing a SQL Plan Baseline fleet cleanup, I wanted to get the SQL_ID give a SQL Plan Baseline. Long ago I wrote a PL/SQL function that inputs some SQL Text and outputs its SQL_ID . Then, I could use such function, passing the SQL Text from the SQL Plan Baseline (this is on 12c), and getting back the SQL_ID I need!

I tested this query  below on 12.1.0.2, and it gives me exactly what I wanted: Input a SQL Plan Baseline, and output its SQL_ID. And all from a simple SQL query. Enjoy it! 🙂

/* from https://carlos-sierra.net/2013/09/12/function-to-compute-sql_id-out-of-sql_text/ */
/* based on http://www.slaviks-blog.com/2010/03/30/oracle-sql_id-and-hash-value/ */
WITH 
FUNCTION compute_sql_id (sql_text IN CLOB)
RETURN VARCHAR2 IS
 BASE_32 CONSTANT VARCHAR2(32) := '0123456789abcdfghjkmnpqrstuvwxyz';
 l_raw_128 RAW(128);
 l_hex_32 VARCHAR2(32);
 l_low_16 VARCHAR(16);
 l_q3 VARCHAR2(8);
 l_q4 VARCHAR2(8);
 l_low_16_m VARCHAR(16);
 l_number NUMBER;
 l_idx INTEGER;
 l_sql_id VARCHAR2(13);
BEGIN
 l_raw_128 := /* use md5 algorithm on sql_text and produce 128 bit hash */
 SYS.DBMS_CRYPTO.hash(TRIM(CHR(0) FROM sql_text)||CHR(0), SYS.DBMS_CRYPTO.hash_md5);
 l_hex_32 := RAWTOHEX(l_raw_128); /* 32 hex characters */
 l_low_16 := SUBSTR(l_hex_32, 17, 16); /* we only need lower 16 */
 l_q3 := SUBSTR(l_low_16, 1, 8); /* 3rd quarter (8 hex characters) */
 l_q4 := SUBSTR(l_low_16, 9, 8); /* 4th quarter (8 hex characters) */
 /* need to reverse order of each of the 4 pairs of hex characters */
 l_q3 := SUBSTR(l_q3, 7, 2)||SUBSTR(l_q3, 5, 2)||SUBSTR(l_q3, 3, 2)||SUBSTR(l_q3, 1, 2);
 l_q4 := SUBSTR(l_q4, 7, 2)||SUBSTR(l_q4, 5, 2)||SUBSTR(l_q4, 3, 2)||SUBSTR(l_q4, 1, 2);
 /* assembly back lower 16 after reversing order on each quarter */
 l_low_16_m := l_q3||l_q4;
 /* convert to number */
 SELECT TO_NUMBER(l_low_16_m, 'xxxxxxxxxxxxxxxx') INTO l_number FROM DUAL;
 /* 13 pieces base-32 (5 bits each) make 65 bits. we do have 64 bits */
 FOR i IN 1 .. 13
 LOOP
 l_idx := TRUNC(l_number / POWER(32, (13 - i))); /* index on BASE_32 */
 l_sql_id := l_sql_id||SUBSTR(BASE_32, (l_idx + 1), 1); /* stitch 13 characters */
 l_number := l_number - (l_idx * POWER(32, (13 - i))); /* for next piece */
 END LOOP;
 RETURN l_sql_id;
END compute_sql_id;
SELECT compute_sql_id(sql_text) sql_id, signature
  FROM dba_sql_plan_baselines
/