34 lines
1.2 KiB
MySQL
34 lines
1.2 KiB
MySQL
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/*
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Description - Converts SQLID into HASH_VALUE
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Input Parameter - SQL_ID
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Source - http://blog.tanelpoder.com/2009/02/22/sql_id-is-just-a-fancy-representation-of-hash-value/
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Basically all it does is takes the SQL ID, interpret it as a 13 character base-32 encoded number and then take only the lowest 4 bytes worth of information (4 bytes in base-256) out of that number and that’s the hash value.
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Actually, since 10g the full story goes like this:
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1) Oracle hashes the library cache object name with MD5, producing a 128 bit hash value
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2) Oracle takes last 64 bits of the MD5 hash and this will be the SQL_ID (but it’s shown in base-32 for brevity rather than in hex or as a regular number)
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3) Oracle takes last 32 bits of the MD5 hash and this will be the hash value (as seen in v$sql.hash_value).
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In 10gR1+, you can do this:
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SQL> select dbms_utility.SQLID_TO_SQLHASH(‘btxdhy7gkbwjk’) hash_value FROM DUAL;
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HASH_VALUE
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———-
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3743806002
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*/
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select
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lower(trim('&&1')) sql_id
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, trunc(mod(sum((instr('0123456789abcdfghjkmnpqrstuvwxyz',substr(lower(trim('&&1')),level,1))-1)
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*power(32,length(trim('&&1'))-level)),power(2,32))) hash_value
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from
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dual
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connect by
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level <= length(trim('&&1'))
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/
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