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Databases,Tables, Views, Indexing and SQL syntax
>>ok.. we are very hard pressed for space on a database that has to fit onto a single cd. we have played with changing large char fields to memo fields and in some cases it saves space, other times it seems to make the database bigger. Does a memo field with say 10 char take up more space than say a char field with 10 char.. is there a rule of thumb as to how much space a memo field will take up (empty one)
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>Memo fields have a permanent 4 byte overhead in the DBF whether they are filled or not. When a memo field is filled, it has blocks of space (I think the default is 64 byte blocks) allocated in the .FPT file. IOW:
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>An empty memo field takes up 4 bytes in the .DBF per record.
>A non-empty memo field takes the same 4 bytes, plus the minimum number of blocks needed to store the value. A 1 byte value will occupy 1 block in the .FPT file, so if blocks are 64 bytes in length, a 1 byte long value takes up (4 + 64) bytes of storage. And there's some overhead involved in chaining blocks together.
what are the effects of block chaining with SET BLOCKSIZE TO 0?
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