- The presentation in PDF format.
- Publishing Landsat on AWS, the use of cloud infrastructure for public data distribution and processing.
- On the size of Google Maps, now larger than most national mapping agencies.
- OpenTripPlanner and OpenStreetMap, how open data and open source leverage each other and are in turn re-consumed by governmnet and civil society.
- Michael H Goldhaber on the attention economy, a prescient take on content and the internet from 1997.
- Google aquires Skybox Imaging.
- Bibiana McHugh on Portland Trimet's [triple open strategy](https://prezi.com/vmydw-uwqalm/copy-of-you-complete
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############################################################################### | |
# AWS compute optimized instance, 16vcpu, 30gb ram | |
############################################################################### | |
# how many trips indexed? | |
# | |
# 15M, 22ms | |
# 26M, 50ms | |
# 39M, 80ms | |
# 54M, 93ms |
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Manhatten east of Lincoln Tunnel | |
14, 4824, 6157 | |
---------------------------------------------------------------------- | |
Tile creation: | |
SELECT Count(*) from ( | |
SELECT Count(1) AS count | |
,floor(256*(((2^14)*(20037508 + ST_X(the_geom_webmercator))/40075016)::numeric % 1)) AS x |
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CREATE OR REPLACE FUNCTION public.CDB_Delayed_TableMetadata_Trigger() | |
RETURNS trigger AS $$ | |
DECLARE upd timestamp; | |
BEGIN | |
IF TG_RELID = 'cartodb.CDB_TableMetadata'::regclass::oid THEN | |
RETURN NULL; | |
END IF; | |
SELECT updated_at INTO upd | |
FROM cartodb.CDB_TableMetadata WHERE tabname = TG_RELID::regclass; | |
IF upd IS NOT NULL AND (now() - upd) > '20m'::interval THEN |
PostgreSQL Parallel Sequence Scan was committed into the git master a couple weeks ago, and initial tests have been promising.
So far, the parallel functionality is only very limited, just sequence scans, but that's still enough to test out against basic PostGIS functions.
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DO $d$ | |
BEGIN | |
EXECUTE $$CREATE SERVER loopback FOREIGN DATA WRAPPER postgres_fdw | |
OPTIONS (dbname '$$||current_database()||$$', | |
port '$$||current_setting('port')||$$' | |
)$$; | |
END; | |
$d$; | |
CREATE USER MAPPING FOR CURRENT_USER SERVER loopback; |
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-- An example of a lateral join driving a nearest-neighbor | |
-- distance calculation | |
SELECT | |
parcels.*, | |
-- keep the hydrant id around, might be useful later | |
hydrants.cartodb_id as hydrant_cartodb_id, | |
-- calculate distance over the spheroid using geography distance | |
ST_Distance(geography(hydrants.the_geom), geography(parcels.the_geom)) as distance | |
FROM | |
-- for this data, removing the duplicate parcel geometries and |
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# pgsql built with USE_VALGRIND | |
# OSX 10.11, valgrind from svn trunk | |
Butterfly:~/Code/postgresql-9.5.0 pramsey$ valgrind --leak-check=no --gen-suppressions=all \ | |
--suppressions=src/tools/valgrind.supp --time-stamp=yes \ | |
--log-file=$HOME/pg-valgrind/%p.log --trace-children=yes \ | |
postgres \ | |
--log_line_prefix="%m %p " \ | |
--log_statement=all \ | |
--shared_buffers=64MB 2>&1 | tee $HOME/pg-valgrind/postmaster.log |
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-- Run against https://github.com/pramsey/postgis/tree/kmeans | |
CREATE TABLE g (id integer, g geometry); | |
INSERT INTO g | |
WITH r AS ( | |
SELECT random() u1, random() u2 FROM generate_series(1,10) | |
), | |
xy AS ( | |
SELECT a + sqrt(-2*ln(u1))*cos(2*pi()*u2) AS x, |
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max_parallel_degree 0 | |
Sets the maximum degree of parallelism for an individual parallel | |
operation. Note that the requested number of workers may not actually | |
be available at runtime. Parallel workers are taken from the pool | |
of processes established by `max-worker-processes` | |
parallel_tuple_cost 0.1 |