On Apr 15, 2020, at 4:35 PM, John J Foster via 4D_Tech <[email protected]>
wrote:
>
> I do believe that creating it locally and moving to the network drive can be
> more efficient. I’m not sure how much speed different there would be.
>
>> using TEXT TO BLOB with the offset parameter
>
> I’m investigating this command and seeing if I can understand how to use it.
If your machine is on an SSD, there will probably be little difference between
writing each row with SEND PACKET or buffering using a BLOB. If you want to
buffer using a blob, the general strategy is like this:
// Calculate rough target size of blob plus a little extra. If 2.3M rows was
830MB, you are at roughly 2700 rows per MB, so maybe calculate 1MB per 2500 rows
$blobSize:=(number of records / 2500)*(1024*1024)
SET BLOB SIZE($buffer;$blobSize)
$offset:=0
For ($i;1;number of records)
// build line into $line
// make sure we have enough space in the blob
If (Blob size($buffer)<($offset+Length($line))
$blobSize:=$blobSize+(Length($line)*2000)// increase by enough that we
don’t have to do it often
SET BLOB SIZE($buffer;$blobSize)
End if
TEXT TO BLOB($line;$buffer;UTF8 text without length;$offset)
End for
// Truncate blob to correct length
SET BLOB SIZE($buffer;$offset) // blobs are zero-indexed
Jim Crate
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