mbtiler: use Wall mode and create index on tiles

[DoFabien]

Hello, Great job! But writing the tiles to the database is so slow ... You can increase by 10 just by using WALL MODE of sqlite

Create index on tiles for efficient access to this table

[andrewharvey]

Whoah that's amazing.

[DoFabien]

I lied. For my test, I used a MNT 5 meters from "la Réunion" (epsg: 3857, 132Mo) With the original version, it took 1470 seconds With conn.execute('pragma journal_mode=wal'), 432s (only 3.4x faster)

But with the commit correctly placed, after the inserts, it took 76s about 20 times faster

PS: The input/output data are on my big and slow external HDD (5200 t/m)

[jdesboeufs]

Any update? It is definitely a very good idea!

[kannes]

I'd suggest to create the index after the tiles have been created. There does not seem to be any use of it during tile creation and it would have to be updated many times during that process.