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https://issues.apache.org/jira/browse/OAK-28?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Dürig updated OAK-28:
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Component/s: jcr
Description:
A query engine needs to be implemented.
A query parser in oak-core should be able to handle xpath, sql2 and optionally
other query languages. The jcr component must generate a valid query in one of
those languages from JQOM queries and pass that statement along with name space
mappings to the oak-core.
We need to:
* Define the oak-core API for handling queries. How are do we handle name space
mappings, limit and size
* Implement a query builder in the jcr component which takes care of
translating JQOM queries
* Implement a query parser in oak-core and decide on a versatile AST
representation which works with all query languages and which is extensible to
future query languages.
* Implement the actual query execution engine which interprets the query AST
was:
A query engine needs to be implemented.
This includes a query parser in oak-core (where we don't want to use the JCR
API), and a query parser in oak-jcr (where the parsed query tree needs to
implement the JCR API).
To avoid writing two independent parsers, I suggest to change the parser to
emit a non-JCR query tree (so the parser can be used in oak-core). There needs
to be a converter from the non-JCR query tree to a JCR query tree, so the same
parser can be used in oak-jcr.
This will still require two independent query tree implementations (about 37
duplicated classes: 37 classes for oak-core and 37 classes in oak-jcr). Plus it
requires a tree converter.
If somebody has a better idea please tell me :-)
Prototype implementation of the query tree converter. Please note the class
names are only to for illustration, but I don't know yet a good naming
convention. Ideas are welcome!
> Query implementation
> --------------------
>
> Key: OAK-28
> URL: https://issues.apache.org/jira/browse/OAK-28
> Project: Jackrabbit Oak
> Issue Type: New Feature
> Components: core, jcr
> Reporter: Thomas Mueller
> Assignee: Thomas Mueller
> Attachments: OakToJcrQueryTreeConverter.java
>
>
> A query engine needs to be implemented.
> A query parser in oak-core should be able to handle xpath, sql2 and
> optionally other query languages. The jcr component must generate a valid
> query in one of those languages from JQOM queries and pass that statement
> along with name space mappings to the oak-core.
> We need to:
> * Define the oak-core API for handling queries. How are do we handle name
> space mappings, limit and size
> * Implement a query builder in the jcr component which takes care of
> translating JQOM queries
> * Implement a query parser in oak-core and decide on a versatile AST
> representation which works with all query languages and which is extensible
> to future query languages.
> * Implement the actual query execution engine which interprets the query AST
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