On 2018-01-25 13:51, Gene Wirchenko wrote:
At 08:15 2018-01-25, mbsoftwaresolutions@mbsoftwaresolutions.com wrote:
On 2018-01-24 18:39, Fernando D. Bozzo wrote:
When the index is evaluated initially, VFP knows exactly what fields affect what index, so really just affected indexes are updated. It's easy to test it. just make an old index (IDX) on two different fields: CREATE TABLE test (field1 C(10), field2 I) INDEX on field1 TO test_f1 additive INDEX on field2 TO test_f2 additive Add some data, wait a minute, replace one of the fields and do a FLUSH FORCE, and you will see that only the affected index changes his timestamp.
I don't think that's a fair test to use IDX files since this example uses a CDX file, and it's all in the same file.
I think it *is* a fair test for exactly that reason. If you seeonly one of the IDX index files change, that suggests that VFP only updates an index where it would make a difference.
I grant that it could be that that optimisation does not exist inthe CDX handling, but how likely do you think that is?
Perhaps a better question at this point: Does the CDX file get pulled down locally for every query? I would think for ADD/UPDATE/DELETEs, it would get updated on the LAN. (In this scenario, the database is on a network folder; not local.)