Bug in TZSQLMetadata resultset caching

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Fresh Boarder
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Posts: 6
Joined: 07.04.2018, 20:47

Bug in TZSQLMetadata resultset caching

Postby ga301 » 14.04.2018, 15:57


I think I may have tracked down the cause for the problem I reported in http://zeoslib.sourceforge.net/viewtopic.php?f=40&t=73973:
It seems that the metadata TZVirtualResultset which has been cached for some combination of tablename and property will be closed, when TZSQLMetadata.Close is called. So, if I want to use TZSQLMetadata to get some info for a table and at a later time I want to get the same info again, this will not work, because the cached resultset has been cleared.
There is actually a guard (property DoNotCloseResultset) which could be used to prevent this in the special case where a resultset is cached.

So I tried the following and it seems to work:

1. In ZAbstractRODataset.pas modify the property declaration of DoNotCloseResultset (make it writable):

Code: Select all

property DoNotCloseResultset: Boolean read FDoNotCloseResultset write FDoNotCloseResultset;

2. In ZSqlMetadata.pas, override the InternalClose method:

Code: Select all

TZSQLMetadata = class(TZAbstractRODataset)
    procedure InternalClose; override;

Code: Select all

procedure TZSQLMetadata.InternalClose;
  DoNotCloseResultSet := true;

I have not yet checked if this introduces any memory leaks or affects other components, but I do not think that it should.

Can somebody please approve and include this fix (or anything else that targets this problem)?
Thank you very much.

Best regards

Gold Boarder
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Posts: 671
Joined: 17.01.2011, 14:17

Re: Bug in TZSQLMetadata resultset caching

Postby marsupilami » 27.04.2018, 07:50

Hello Gunnar,

Egonhugeist told me that the problem should be fixed in the Zeos 7.2 branch by now as well. Could you please try that?
With best regards,


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