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Date: Mon, 02 Oct 2017 13:48:27 +1300
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Subject: Re: [PHP-DEV] Re: [RFC] [Discussion] Implement SQLite "openBlob"  feature in PDO
From: php@bohwaz.net (BohwaZ/PHP)

>> PDO already has support for large objects (LOBs)[1].  I don't know if
>> and how these are supported by the pdo_sqlite driver, but wouldn't it
>> make sense to use the existing API instead of introducing a new
>> method?
>> 
>> [1] <http://www.php.net/manual/en/pdo.lobs.php>
>> 
> 
> Very interesting indeed, didn't know about that feature, I was
> expecting the creation of a new method was the only way, as this was
> the way PGSQL was doing it.
> 
> There's even a bug report about it:
> https://bugs.php.net/bug.php?id=57691
> 
> I will look into that next week and see if it can fit and replace my 
> RFC
> then.


OK, I took some time to look into that feature and the fact is that it 
doesn't work at all currently with SQLite, it is not returning a 
resource handle but a string, and it is consuming a large amount of 
memory as it is just dumping the LOB in memory. The code seems to be 
there to handle it though so I don't know what's going on, if the person 
who implemented that could come forward and tell me more about the 
implementation.

But I tried it and it doesn't cover one of the use of openBlob that I 
have which is to open, read, and write at the same time.

The current way it's done in PDO is that you can either fetch a LOB from 
a result of a query and read from it, or bind a file resource handler to 
a statement for writing, but you cannot open a LOB, read from it and 
write from it without performing a query.

So for me the use case is quite different here, and openBlob allows 
stuff that PDO::PARAM_LOB with bindColumn and bindParam cannot allow 
currently. In conclusion openBlob is still useful as it allows accessing 
a BLOB outside of a statement and allows to read and write at the same 
time without having to load the blob in memory.