WMS-Time support in PostGIS rewrite

[pramsey]

The current time support is inelegant in implementation, and inefficient to boot. As reported by a user, the queries of the form

date_trunc('resolution', datecolumn) <= 'querytime' and date_trunc('resolution', datecolumn) >= 'querytime'

have the effect of rendering indexes on the datecolumn ineffective. The correct way to write the query is

datecolumn >= 'querytime' and datecolumn <= 'querytime' + 'resolution'::interval

In general the PgSQL interval syntax is called for here and date_trunc should be dropped (except maybe for rounding the querytime prior to applying the interval, if necessary).

Also, breaking the implementation down into smaller parts would probably make it a lot less intimidating and amenable to future maintenance.

[tbonfort]

fixed in r12568

I also took the liberty of refactoring the time code into different modules.

Slightly modified msautotest wms_time tests to use postgis connections pass with these changes. There are a serie of tests that do not pass, but they indicate that the shapefile time support is broken rather than the rewritten postgis queries (those tests also fail with the previous postgis implementation)

[tbonfort]

closing. subsequent postgis time bugs should be reported in their own ticket.

[tbonfort]

really closing