Re: FetchSpec setFetchLimit??
Re: FetchSpec setFetchLimit??
- Subject: Re: FetchSpec setFetchLimit??
- From: Kieran Kelleher <email@hidden>
- Date: Mon, 2 Mar 2009 19:26:36 -0500
Hi Chuck,
I was half-expecting this outcome, especially after examining how the
different SQLHelpers implement limitSqlExpression method. I am tempted
to implement an ERXSpec subclass though to auto limit for databases
with supported ERXSqlHelpers ...... it just seems like the right
default behaviour to have....
Thanks, Kieran
On Mar 2, 2009, at 6:43 PM, Chuck Hill wrote:
On Mar 2, 2009, at 1:42 PM, Kieran Kelleher wrote:
I always thought that EOFetchSpecification.setFetchLimit( int n)
would generate SQL with LIMIT n tacked onto the end of the SQL
statement, but it appears not to.
This is the default behavior as not all databases implement this.
Specific plugins add this, IIRC.
Chuck
Instead it fetches the all qualifying records and does the LIMIT in
memory?! Has this always been the case .... or is it just the MySQL
driver?
For example:
<snip>
// Fetch the most recent shipped message
ERXSortOrderings s = CTMessage.XKEY_OID.descs();
ERXFetchSpecification<CTMessage> fs = new
ERXFetchSpecification<CTMessage>(CTMessage.ENTITY_NAME,null,s);
fs.setFetchLimit(1);
System.out.println("MailingAddressUtilitiesTests.suppressionTest():
fs.SQL = " + ERXEOAccessUtilities.sqlForFetchSpecification(ec, fs));
NSArray<CTMessage> objects = fs.fetchObjects(ec);
</snip>
..... generates the following SQL without "LIMIT 1" !!!
SELECT t0.oid, t0.oidcampaign, t0.oiddatarecord, t0.oidjob,
t0.oidlocation, t0.oidmediatemplate, t0.recaddtime, t0.recadduser,
t0.recmodtime, t0.recmoduser, RTRIM(t0.workflowstate) FROM message
t0 ORDER BY t0.oid DESC;
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--
Chuck Hill Senior Consultant / VP Development
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems.
http://www.global-village.net/products/practical_webobjects
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