Critical Tegola bugs

[pnorman]

Tegola has some critical bugs that prevent a number of essential things in the style. This meta-issue is to track them

Critical bugs

These are serious enough to prevent release, and do not have acceptable workarounds.

SQL type sniffing

• [x] Tegola uses LIMIT 1 to look at a row (go-spatial/tegola#320). This prevents ordering in the roads layer.
• [x] function(!ZOOM!) and !ZOOM! < n cause syntax errors (go-spatial/tegola#343). This prevents filtering by area depending on zoom.

Output bugs

• [x] Missing water polygon (go-spatial/tegola#348)

Major

These don't prohibit release, but cause major problems or have bad workarounds

Output bugs

• [ ] Geometry corrupted by simplification (go-spatial/tegola#341).
• [x] Tiles missing data when multiple rows have same id (go-spatial/tegola#337) is part of the cause of the extra sub-select all the queries have.

Major enhancements

These make something which is currently difficult or messy significantly better.

• [ ] Merging multiple layers (go-spatial/tegola#127). This would eliminate most of the UNION ALLs
• [x] Don't require ID field for layers (go-spatial/tegola#338)
• [ ] Best practices for deploying Tegola (go-spatial/tegola#356) is not blocking code release, but blocks any public demo.