On 2018-01-25 13:51, Gene Wirchenko wrote:
At 08:15 2018-01-25, [email protected] 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 see
only 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 in
the 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.)
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