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geodatabases

PostGIS function ST_buffer – using QGIS, PostGIS, and PostgreSQL

PostGIS function ST_buffer – using QGIS, PostGIS, and PostgreSQL

We will utilize the PostGIS function ST_buffer to determine which residential areas on the San Jacinto River on the downstream side would be affected by a dam breach or a substantial release from lake Conroe. We have had major flooding throughout Texas in the past few weeks and the lake Conroe dam has been getting repairs due to erosion and ...

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Mending Spatial Data with PostGIS

Mending Spatial Data with PostGIS

This presentation demonstrates common techniques to clean-up spatial data from a real-world data source. It will start with raw OSM data. Topics it’ll cover: Getting OSM data How to merge multilinestrings into single linestrings. Fill in gaps, snapping, reducing resolution Consolidating geometries with aggregate functions ST_Union, ST_MakeLine, ST_Collect based on both spatial and non-spatial attributes

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Explaining the Postgres Query Optimizer

Explaining the Postgres Query Optimizer

The optimizer is the “brain” of the database, interpreting SQL queries and determining the fastest method of execution. This talk uses the explain command to show how the optimizer interprets queries and determines optimal execution. The talk will assist developers and administrators in understanding how Postgres optimally executes their queries and what steps they can take to understand and perhaps ...

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MySQL 5.7: a GIS Reborn

MySQL 5.7: a GIS Reborn

MySQL is reemerging within the spatial world in version 5.7 as we replace much of the old foundation by incorporating Boost.Geometry, by adding R-tree index support to the InnoDB engine, and by adding a number of helper functions (e.g. ST_Distance_Sphere). We’ve also begun paving the way for even more functionality moving forward, such as Projections and Geography. This video¬†will walk ...

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PostgreSQL Performance Presentation

PostgreSQL Performance Presentation

This presentation will take a look at the performance changes in the development version of PostgreSQL. A selection of features, some proposed and some already committed, are evaluated using synthetic open source workloads. One of the workloads used is the former OSDL’s Database Test 3 that consists of business oriented ad-hob queries with concurrent data modification. Some of these proposed ...

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Magical PostGIS in three brief movements

Magical PostGIS in three brief movements

Everyone knows you can query a bounding box or even spatially join tables in PostGIS, but what about more advanced magic? This short symphony of PostGIS examples will look at using advanced features of PostGIS and PostgreSQL to accomplish surprising results: Using full text search to build a spatially interactive web form. Using raster functionality to look into the future. ...

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Writing better PostGIS queries

Writing better PostGIS queries

This presentation will demonstrate ways to take most advantage of spatial indexes, SQL constructs, and PostGIS specific functions. For these exercises we’ll be using PostGIS 2.1+ and PostgreSQL 9.3+ . We’ll demonstrate common cases people often do inefficiently. This presentation demonstrates the following 1) Various SQL constructs including ANTI join, LEFT, RIGHT, EXISTS, LATERAL, CASE clauses, aggregates 2) What common ...

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What can PostGIS do ?

What can PostGIS do ?

What can PostGIS do? What features does it have? What has changed in recent versions? What new features are upcoming in future releases? This talk will cover the history and development of the PostGIS spatial database server.

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