Bug report #582
Use the estimateExtents function for PostGIS and PostgreSQL 8
| Status: | Closed | ||
|---|---|---|---|
| Priority: | Low | ||
| Assignee: |  Jürgen Fischer | ||
| Category: | Data Provider | ||
| Affected QGIS version: | Regression?: | No | |
| Operating System: | All | Easy fix?: | No |
| Pull Request or Patch supplied: | Resolution: | fixed | |
| Crashes QGIS or corrupts data: | Copied to github as #: | 10641 |
Description
Currently the POSTGIS data provider use the "extents" function to determine the layers spatial extents. This can take time on very large tables. Starting from PostgreSQL 8.0 the column's statistics are stored. This means that the geometry extents can be cached during statistic gathering. The POSTGIS team have added a function that returns the estimated extents "estimateExtents".
This function should be used by the data provider when the server version is greater than 8.0.
The inconvenience of not having the precise extent does not out weight the need for quick data provider creation. If it becomes an issue for the user the database admin should schedule regular table statistics updates.
Associated revisions
postgres provider update
- track open cursors and commit transaction whenever no open cursors are left
- close cursor after immediately after feature retrieval (releases locks earlier)
- wrap postgres calls in Conn class
- introduce Result class to handle PQclear mostly transparently (fixes minor leaks)
- remove executeDbCommand method (duplicate of PQexecNR)
- introduce support for estimate_extents (fixes #582)
- introduce support for enum types (fixes #1210)
git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@9183 c8812cc2-4d05-0410-92ff-de0c093fc19c
postgres provider update
- track open cursors and commit transaction whenever no open cursors are left
- close cursor after immediately after feature retrieval (releases locks earlier)
- wrap postgres calls in Conn class
- introduce Result class to handle PQclear mostly transparently (fixes minor leaks)
- remove executeDbCommand method (duplicate of PQexecNR)
- introduce support for estimate_extents (fixes #582)
- introduce support for enum types (fixes #1210)
git-svn-id: http://svn.osgeo.org/qgis/trunk@9183 c8812cc2-4d05-0410-92ff-de0c093fc19c
History
#1
Updated by Aaron Racicot - about 17 years ago
- Status changed from Open to In Progress
#2
Updated by Jürgen Fischer over 16 years ago
- Status changed from In Progress to Open
#3
Updated by Jürgen Fischer about 16 years ago
- Resolution set to fixed
- Status changed from Open to Closed
added in b9452c2d (SVN r9184)
#4 Updated by Anonymous over 15 years ago
Milestone Version 1.0.0 deleted