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I think it might be:

Query.Properties.Add('BinaryWireResultMode=false');

to force the character mode data handling. I haven't need to use it though so it would be great to find out the data or type that causes the issue.

-Mark

Looks good to me!

-Mark

Found it. In the constructor for TZCodePageConversionStream it checks the size of the stream. The problem is that this is before the TemporaryLob has been created (which happens in "BeforeWrite".) A quick fix is to check for this specific case in the lobsteam's GetSize and return zero. Thi...

I should add that my dev environment is Delphi 11.3 and my Oracle Client is 21.8 with an Oracle 19 server.

-Mark

Sample code to show the two bugs: program ZeosOraClobUTF8; {$APPTYPE CONSOLE} {$R *.res} uses System.SysUtils, System.Classes, System.Diagnostics, ZDbcIntfs, ZDbcProperties, ZConnection, ZDataset; var ZConn: TZConnection; ZQuery: TZQuery; TempString: String; i: integer; RecID: Integer; RecAClob: Str...

Hey all! I've been doing some work in the Oracle part of Zeoslib relatd to clobs. I have changes almost ready to show but ran into a couple bugs when testing in UTF8 mode. It was driving me bonkers until I realized that the bugs also exist in the current code and weren't caused by my new stuff. It l...

Hi Jan,

Sorry! I guess I was impatient! All good and thanks as always.

-Mark

Hey all,

is the github repo active? It seems to be a few weeks behind. Thanks!

-Mark

Update: Lab results... looking good!

Fascinating! The copy is absolutely needed (at least for now.) Zeos uses the same allocated loblocators for each "rowbatch" fetch. In OnLoad cache mode the loblocators are used directly to fetch the individual row clobs (before they're overwritten by the next "rowbatch" fetch) so...

Revisiting this after my testing related to clob performance. It seems that the combination of UTF8, Zeos' default blob prefetch size (8k), and cachemode of "onLoad" causes an access violation. Setting the prefetch to a size larger than any of your clobs causes empty strings to be returned...

Hi all, I've been doing some testing on Clobs and found that with cache modes of None or OnAccess that retrieving clobs is three to four times slower than when using OnLoad caching. I managed to gain a little performance by consolidating some of the OCILobGetLength2 calls, but it took a while to fig...

I've uploaded that test.

I had missed the suggestion to try TZDataSet.Properties.Values[DSProps_UseResult] := 'True'; and adding that fixes the issue for TZReadOnlyQuery and also for TZQuery with ReadOnly := True. With that change the sorts all take about 250ms in my test.

-Mark

Hi Jan, I've been trying to post a console mode program that shows the issue and I keep getting rejected by the forum security checker. I've been able to do it in the past. They seem to have dialed up the security settings so high that just simple sql statements seem to trigger it. I also can't seem...

Ok, I'm a smidge slow on testing this! I had abandoned the idea of using TZReadOnlyQuery or setting ReadOnly to true for TZQuery. However, recently while looking at ZMemTable, I revisited this (and found this post) and the issue still seems to exist. Setting DSProps_MinExecCntBeforePrepare to '0' se...