postgresql-9.3

Does PostgreSQL provide any notation/method for putting a constraint on each element of a JSON array? An example: create table orders(data json); insert into orders values (' { "order_id": 45, "products": [ { "product_id": 1, "name": "Book" }, { "product_id": 2, "name": "Painting" } ] } '); I can easily add a constraint on the order_id field: alter table orders add check ((data->>'order_id')::integer >= 1); Now I need to do the same with product_id . I can put constraint on idividual array items: alter table orders add check ((data->'products'->0->>'product_id')::integer >= 1); alter table

I use Apartment gem in Rails 4 to support multi-tenancy in Postgres 9.3.3 on Heroku. An error is occurred when Apartment gem creates a new tenant. Deep investigation showed that a schema was created, but no tables inside. Heroku logs showed an error: PG::Error: ERROR: function pg_stat_statements_reset() does not exist When a new schema is created Postgres is trying to reset stats by executing the function pg_stat_statements_reset() By default, this function can only be executed by superusers (from original doc) . Heroku doesn't give you superuser privileges. So you need to disable extension pg

I am new to Postgres and just discovered that I cannot access data of different databases in one SQL query. And also learned the concept of schema in Postgres. Now, I have two databases db1 and db2 Both have tables with same name in their public schema. Now, I want to create a new schema in db1 with name : new_schema And move data from db2.public to db1.new_schema What is the easiest way to do this ? The simplest way to do that is to rename schemas. However you must be sure you are a sole user of db1 database. First, hide your schema public in db1: alter schema public rename to original_public

I want to index data in height dimensions (128 dimensional vectors of integers in range of [0,254] are possible): | id | vector | | 1 | { 1, 0, ..., 254} | | 2 | { 2, 128, ...,1} | | . | { 1, 0, ..., 252} | | n | { 1, 2, ..., 251} | I saw that PostGIS implemented R-Trees. So can I use these trees in PostGIS to index and query multidimensional vectors in Postgres? I also saw that there is a index implementation for int arrays . Now I have questions about how to perform a query. Can I perform a knn-search and a radius search on an integer array? Maybe I also must define my own distance function.

Using PostgreSQL 9.3, I want to convert the calculated values to data type float . My first attempt: SELECT float(SUM(Seconds))/-1323 AS Averag; Gives me this error: syntax error at or near "SUM" My second attempt: SELECT to_float(SUM(Seconds))/-1323 AS Averag; Gives me this error: function to_float(bigint) does not exist You need to use the cast syntax: SELECT CAST (SUM(Seconds) AS FLOAT)/-1323 AS Averag; Erwin Brandstetter There is also the shorthand cast syntax: SELECT sum(seconds) ::float / -1323 AS averag; Postgres data type cast It is not exact casting but a trick to do the job :) and