IBM® Informix® 12.10

Multitable query

For join plans, the OPTCOMPIND setting influences the access plan for a specific ordered pair of tables.

Set OPTCOMPIND to 0 if you want the database server to select a join method exactly as it did in previous versions of the database server. This option ensures compatibility with previous versions.

If OPTCOMPIND is set to 0 or set to 1 and the current transaction isolation level is Repeatable Read, the optimizer gives preference to the nested-loop join.
Important: When OPTCOMPIND is set to 0, the optimizer does not choose a hash join.

If OPTCOMPIND is set to 2 or set to 1 and the transaction isolation level is not Repeatable Read, the optimizer chooses the least expensive query plan from among those previously listed and gives no preference to the nested-loop join.

Parent topic: Effect of OPTCOMPIND on the query plan

Examples exchange | Troubleshooting

To find the PDF, see Publications for the IBM Informix 12.10 family of products.
For the release notes, documentation notes, and/or machine notes, see the Release Notes page.