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Append blank VS insert SQL
Message
De
23/03/2005 05:37:36
Cetin Basoz
Engineerica Inc.
Izmir, Turquie
 
 
À
22/03/2005 20:16:13
Dragan Nedeljkovich (En ligne)
Now officially retired
Zrenjanin, Serbia
Information générale
Forum:
Visual FoxPro
Catégorie:
Autre
Divers
Thread ID:
00998018
Message ID:
00998356
Vues:
12
>>>and what about speed ?
>>>I made a test and seems like append was 4 to 10 times slower
>>
>>I wouldn't comment on that. From test to test one might be faster than the other. My reasoning is simple:
>>
>>select myTable
>>Append Blank
>>replace field1 with m.somevalue, ...
>>
>>vs:
>>
>>insert into myTable (field1, ...) values (m.somevalue, ...)
>>
>>latter is a single atomic operation. Insert into also have variations like "insert into ... from memvar|array".
>>
>>It has been a long time I don't use 'Append Blank'.
>
>I'd only add one more thing: since the table is very likely to have indexes, the indexes need to be updated too. With append blank, we're writing blanks into the fields and indexes, then during a replace we're doing it again (and potentially reshuffling some of the b-trees in some of the indexes). So it's not one write vs two writes, it's n writes vs 2*n writes.

Good point:)
Cetin
Çetin Basöz

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