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Indexing Daydream
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Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00213836
Message ID:
00214252
Vues:
42
Rich,

This will build all the indexes at once, but the real penalty is that the internal stucture of the CDX will be highly fragmented. Meaning that nodes of the B+Tree for each key will be spread throughout the whole file. This will cause lots of additional I/O time to read a key when rushmore needs it. If an index is built on the whole table at once the key occupies one contiguous space within the CDX. I think (untested assumption) that the CDX file size will be smaller becuase of the reduced fragmentation.

>Seems to me that this may be faster (and close to what Ken was asking for) if you changed the process to:
>
>1. Build temp table from definition
>2. Index temp table (define indices before import)
>3. Import new data (Fox updates all indexes simultaneously in background)
>4. Rename old table
>5. Rename temp table to live table name
>
>This is untested, just brainstorming, and may be considerably slower, not faster, for all I know. In fact, I may have read tips from various experts (Goley?, Hennig?) that my suggestion is the bad way, and Ken's process is the fast way...
df (was a 10 time MVP)

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