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Key: NUCMONGODB-129
Type: New Feature New Feature
Status: Closed Closed
Resolution: Fixed
Priority: Major Major
Assignee: Unassigned
Reporter: Marcin Jurkowski
Votes: 0
Watchers: 0
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DataNucleus Store MongoDB

Evaluate expressions invoking basic string methods in-database

Created: 16/Nov/13 02:09 AM   Updated: 19/Nov/13 10:29 AM   Resolved: 17/Nov/13 09:00 AM
Component/s: None
Affects Version/s: None
Fix Version/s: 3.2.5

File Attachments: 1. File 0001-Evaluate-basic-string-predicates-in-database.svn.diff (6 kB)


Forum Thread URL: http://www.datanucleus.org/servlet/forum/viewthread_thread,7624
Datastore: MongoDB


 Description  « Hide
Queries invoking the following string methods: equals(), matches(), startsWith(), endsWith() can be evaluated in-database using $regexp operator provided that:
 1. The method is invoked on a field,
 2. The method's parameter is a parameter expression.

It's worth noting that MongoDB will handle a query with startsWith() efficiently using an index, if one exists.

For substring search, the most efficient way is to use matches() predicate, escaping string literal with Java Pattern.quote(). If a case-insensitive query is desirable, escaped string should be prefixed with "(?i)" regexp modifier.

Even though substring search cannot be speed up by an index, having this evaluated in-database still allows a part of query to use index and prevents in-memory query evaluation.


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Marcin Jurkowski added a comment - 16/Nov/13 02:09 AM
A patch

Andy Jefferson added a comment - 16/Nov/13 08:41 AM
This patch doesn't apply cleanly. Please provide a patch ("diff -u" format) that applies from the root of the "store.mongodb/trunk" project.

Marcin Jurkowski added a comment - 17/Nov/13 12:44 AM
What is the version of your patch utility? I checked this out and the diff applies cleanly using both "patch" with -p1 option (I'm using version 2.6.1) and "svn patch" (ver 1.7.13).

Anyway, I'll attach a diff generated by "svn diff" command but the only difference I see is:
 1. The comment section, which should be ignored anyway,
 2. The path prefix in git generated file which needs to be stripped using -p1 option

Marcin Jurkowski added a comment - 17/Nov/13 12:45 AM
A patch generated with "svn diff" against "store.mongodb/trunk" root

Andy Jefferson added a comment - 17/Nov/13 09:00 AM
SVN trunk has this now. Thanks