Replacing materialized view by a tables with update from trigger on change only.
Start with the most simple cases.
Just replicate the change on:
* `osm_water_polygon` to `osm_water_lakeline`,
* `osm_water_polygon` to `osm_water_point`.
Use a view to factorize the `osm_water_lakeline` and `osm_water_point_view` definition and reuse it in the trigger.
The update of `osm_important_waterway_linestring` is more complex, as it is a merge of `osm_waterway_linestring`. It not done in the same way. At the end of the transaction we remove impacted and recompute them.
The goal is to update more quickly the content of derivated table by just updating the changing content. It replaces the update of materialized view because their need a full recompute (with lock issue).
Note, an advanced version of differential update over materialized view as already implemented in the building cluster PR #725.
It addresses #814 and a part of #809.
Mark waterway and transoprtation_name as having a dependency on another layer.
This is currently an unused parameter, but tools will use it later for faster
sql code generation.
Closes#796
This PR allows queries to be parallelized on recent versions of Postgres. The `PARALLEL SAFE` modifier has been added to the layer functions and a PLPGSQL function to convert strings into number has been replaced.
`PARALLEL SAFE` is a modifier for `CREATE FUNCTION` available since Postgres 9.6, so this change does not break current OpenMapTiles supported database version. More details about this topic [here](https://www.postgresql.org/docs/current/parallel-safety.html) and at the reference documentation for [`CREATE FUNCTION`](https://www.postgresql.org/docs/current/sql-createfunction.html).
### Testing procedure
The procedure to test this was:
* Imported `spain.pbf` in a clean environment
* Dumped the OpenMapTiles database from the Postgres Docker image
* Created a clean Postgres 12 database using the default Docker image
* Installed `postgis` 3 from the default Debian package and `osml10n` 2.5.8 from the repository (`make`, etc.)
* Restored the dump
* Lowered the postgres planner parameters for triggering parallel plans:
```sql
set parallel_setup_cost = 5;
set parallel_tuple_cost = 0.005;
```
* Manually added the `PARALLEL SAFE` modifier to each function involved in layer queries (not on updates or inserting functions).
* For each layer, run a testing query to confirm parallel workers were created, something like this:
```sql
explain analyze
select * from layer_aerodrome_label(tilebbox(8,128,95),10,null)
union all
select * from layer_aerodrome_label(tilebbox(8,128,97),10,null);
```
* After all the layers were processed and confirmed to start parallel executions, a more complete example was run. This example just retrieves the geometries for all the layers from the same tile but without using any MVT related function.
<details><summary>Testing query</summary>
```sql
-- Using the function layer_landuse
explain analyze
select geometry from layer_water(tilebbox(14,8020,6178),14)
union all
select geometry from layer_waterway(tilebbox(14,8020,6178),14)
union all
select geometry from layer_landcover(tilebbox(14,8020,6178),14)
union all
select geometry from layer_landuse(tilebbox(14,8020,6178),14)
union all
select geometry from layer_mountain_peak(tilebbox(14,8020,6178),14)
union all
select geometry from layer_park(tilebbox(14,8020,6178),14)
union all
select geometry from layer_boundary(tilebbox(14,8020,6178),14)
union all
select geometry from layer_aeroway(tilebbox(14,8020,6178),14)
union all
select geometry from layer_transportation(tilebbox(14,8020,6178),14)
union all
select geometry from layer_building(tilebbox(14,8020,6178),14)
union all
select geometry from layer_water_name(tilebbox(14,8020,6178),14)
union all
select geometry from layer_transportation_name(tilebbox(14,8020,6178),14)
union all
select geometry from layer_place(tilebbox(14,8020,6178),14)
union all
select geometry from layer_housenumber(tilebbox(14,8020,6178),14)
union all
select geometry from layer_poi(tilebbox(14,8020,6178),14)
union all
select geometry from layer_aerodrome_label(tilebbox(14,8020,6178),14);
```
</details>
You can inspect the execution plan and results on [this page](https://explain.dalibo.com/plan/3z). Also [attaching](https://github.com/openmaptiles/openmaptiles/files/3951822/explain-tile-simple.tar.gz) the query and JSON output for future reference. The website gives a ton of details, but you may want to search for nodes mentioning `workers` or `parallel` like in this area referring to `osm_border` or `osm_aeroway_linestring` entities
### Next steps
Since the execution plan is not showing a parallel append at the top level, meaning it's not running each layer individually, I want to continue experimenting with parameters and queries to see if it's possible to even parallelize more the request.
I will post my finding here, even no change in the code should happen.
cc. @nyurik
Co-authored-by: Yuri Astrakhan <yuriastrakhan@gmail.com>
quicker and cleaner diagram image generation.
Remove etl-graph and mapping-graph targets - redundant
Also, the obsolete "fields" is still in Imposm's code and both names are accepted,
but "fields" is not documented anywhere (PR submitted), and could be removed at any moment.
Our docs were not supporting it until this PR, so renaming it at the same time.
Several images have been updated due to a more inclusive mapping scan
Requires https://github.com/openmaptiles/openmaptiles-tools/pull/147 (merged)
Minor code cleanup:
SQL already returns NULL in the "WHEN" condition
if it is not matched by any of the cases.
Co-authored-by: Eva Jelinkova <evka.jelinkova@gmail.com>
Tag all SQL materialized views with a machine-readable comment
to indicate that this materialized view can be created without
data:
/* DELAY_MATERIALIZED_VIEW_CREATION */
In the next version of tools this comment can be optionally
replaced with the "WITH NO DATA" parameter, thus allowing
a much faster execution of the SQL script. All materialized
viewes will be populated with data in parallel afterwards
using the `refresh-views` tools script.
Seems like etl and mapping diagrams have been neglected
for a long time. Now it regenerates the files and places
them in the source dir.
This PR also fixes two broken files:
* layers/aerodrome_label/mapping_diagram.png
* layers/housenumber/mapping_diagram.png
They were generated using the newest tools version with the fix
https://github.com/openmaptiles/openmaptiles-tools/pull/65
