Hi,
I'm just starting looking into some slow downs in geoserver when adding a
time dimension to a vector layer (i.e. postgis or geogig). By this I mean
editing the layer, going to the "Dimensions" Tab and "Enabling" Time or
Elevation.
A. GetCapabilities gets slow. It does a table scan for each
GetCapabilities request to determine the min/max/unique values of the Time
attribute (depending on how you set things up on the Layer's dimension's
tab).
B. GetMap gets slow. I tracked this down to it doing 2 table scans and an
index scan.
a. It does scan of the data to determine the max time. This is likely
because the default is to have the max date be the "default" in a query;
SELECT max("datemod") FROM "public"."my_dataset"
b.It does a scan of the data to construct a FID-Time Index for the entire
dataset (for each getmap request):
SELECT "gid","datemod" FROM "public"."my_dataset"
c. It then does a (normal) index scan to get data required to draw;
SELECT "gid",encode(ST_AsBinary(ST_Simplify(ST_Force2D("geom"), 15.5,
true)),'base64') as "geom" FROM "public"."my_dataset" WHERE "geom" &&
<polygon>
I haven't look into this in detail - but there's some obvious ways to make
this smarter (i.e. caching time values for a layer like we cache extents -
but that might not be what someone wants).
Has anyone else looked into this? I've seen some earlier discussion, but
nothing too concrete...
Thanks,
Dave
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, SlashDot.org! http://sdm.link/slashdot
_______________________________________________
Geoserver-devel mailing list
Geoserver-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/geoserver-devel
