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5
votes
2answers
102 views

How to verify disk hit by a query

I want to know how to verify disk hits by a select query in PostgreSQL 9.4 on CentOS 6.5. Also please let me know how far enabling the log_statement_stats in the postgresql.conf will help me. I need ...
-2
votes
1answer
73 views

Fatal error when not numeric value - PostgreSQL 9.2 [closed]

Below is an example of the auto-generated update query, with client-supplied keys (_iid). There's a fatal error when _iid is not numeric. However; this should accept any value. I believe that's what ...
2
votes
1answer
106 views

How to estimate reindexing time?

How do you estimate the total time reindexing an entire table will take in PostgreSQL? I have a large PostgreSQL database, the primary table of which has 15 million rows with 100 columns and 200 ...
0
votes
0answers
8 views

How to estimate PostgreSQL reindexing time? [duplicate]

How do you estimate the total time reindexing an entire table will take in PostgreSQL? I have a large PostgreSQL database, the primary table of which has 15 million records and 100 columns, and 200 ...
0
votes
0answers
47 views

Stored procedure vs transaction anomaly

We have a stored procedure which updates reporting data in a table. We call this via Hibernate from Java. Within the stored procedure the current time is taken from the NOW() function. The anomaly ...
1
vote
1answer
43 views

Trigger for removing group with no users left in

I have three tables: USERS, GROUPS, and GROUP_MEMBERSHIP CREATE TABLE USERS ( ID BIGSERIAL NOT NULL, NICKNAME VARCHAR(20) NOT NULL constraint USER_EXISTS UNIQUE, PRIMARY KEY (ID) ); CREATE TABLE ...
4
votes
5answers
720 views

Enforce NOT NULL for set of columns with a CHECK constraint only for new rows

I have a table and need to add a new column without a default value: Constraint: ALTER TABLE integrations.billables DROP CONSTRAINT IF EXISTS cc_at_least_one_mapping_needed_billables, ADD ...
1
vote
1answer
41 views

Plpgsql (Postgres) function for sanity check

While starting up my app, I need to do a sanity check within my database. In a table sensor, there's a column seconds. Now the function should take an argument id. It then should simply do something ...
0
votes
0answers
67 views

Index has no gain vs normal query

I have a table with a timestamp field. The table is loaded with rows which have ascending order of this field (time increases). I tried the following query, prior to establishing an index (there are ...
0
votes
1answer
25 views

PostgreSQL, how to query the database to retrieve the percentile elements of a dataset?

I need a PostgreSQL query that do the following job: given a percentage (e.g. 10%), the query should return each 1st element of each percentile, among all the elements selected. So suppose in this ...
5
votes
2answers
154 views

Trigger to create symmetrical rows

I've got a table that describes some relation between two items. The items are referenced by ID. I'd like to create a trigger, so whenever you create a row (a,b), a symmetrical row (b,a) is created. ...
2
votes
1answer
51 views

How to create an index to be picked by query

I have created multiple indexes one after another, but my query doesn't want to pick them :( CREATE INDEX x ON gan.paid (project_id, country_iso_code, source, date(created_at)); CREATE INDEX x ...
14
votes
1answer
1k views

Why does time zone have such a crazy offset-from-UTC on year 0001 in Postgres?

In Postgres 9.5, I was surprised to see the result seen below while experimenting with year 0001 (no year zero 0000). Offset of -07:52:58? Some example code. Note that I mixed use of TIMESTAMP WITH ...
1
vote
1answer
71 views

Data structure design for supporting arbitrary number of columns in table or database [closed]

I am currently working on a sort-of a meta-modeler to build a free web service so that people can input data and run several models on that data. The task I am currently struggling is: user needs to ...
0
votes
2answers
112 views

PostgreSQL surrogate keys: use sequence/bigint or OID?

I'm looking at a need for surrogate keys in tables I'm designing on a PostgreSQL-derived DBMS (Citus). Would OIDs suffice? Is there a downside to using them instead of creating a bigint field and a ...
3
votes
0answers
80 views

Some delays in heavy inserts

I have a lightweight web-application with current load of about 500 reqests/sec. Almost each request generates an INSERT request to the database. Some time ago I found that my application has short ...
0
votes
1answer
65 views

Getting records for yesterday, but per hour

I am currently getting all data for yesterday from my database but I want to get data for each hour. This is my query: select camera_id, count(*) as snapshot_count from snapshots where ...
4
votes
1answer
399 views

How to design a database

The file which contains the day to day activities of each employee. And it shows the detailed description of employee what they done at work time. So these files are prepared by employee. Now, my ...
5
votes
1answer
117 views

dumping database with “compressed data is corrupt” errors

I'm using pg_dump to dump a large (396 GB) PostgreSQL database: pg_dump --clean --create mydatabase After running for a day, a statement fails with ERROR: compressed data is corrupt and pg_dump ...
0
votes
0answers
32 views

How can I display values as columns dynamically using postgresql

I have a data table containing finance data about some filings like: filing_id | custom_label | value ------------------------------------ 987345 | cash | 567 987345 | ...
1
vote
1answer
82 views

PostgreSQL optimistic reads (equivalent to SQL Server's Read Committed Snapshot)

Does PostgreSQL provide a built-in optimistic concurrency control mechanism such as SQL Server's Read Committed Snapshot Isolation? Readers can read all the rows without blocking, but writes will ...
0
votes
0answers
73 views

Postgres, promoting slave to master issue

We had the following setup in place db01 -> Master Postgres 9.3 db02 -> Slave Postgres 9.3 Master data got corrupted (logically) and as soon as it was identified we shutdown the server. Dev team ...
3
votes
1answer
70 views

Use specific array column in the where clause

Having a function that returns an array and in a query we use the function to return results such as: {"TUNDUMA GOING (BORDER)","ARRIVAL DATE",09/01/2016,22,"AT CHECKPOINT"} {"TUNDUMA RETURN ...
1
vote
1answer
56 views

Postgres CTE query for a single row not optimized

From my database I am trying to get a weighted sum of a user's stats, and I will only be querying the table one or two users at a time, so I wrote it as a view. Since it's a view, I pretend to ...
3
votes
1answer
109 views

Trigger function taking column names as parameters to modify the row

I am trying to write a trigger function in Postgres 9.4. Something like this (not working, yet): CREATE FUNCTION set_point_from_coords(source _regclass, target _regclass) RETURNS trigger AS ...
2
votes
1answer
129 views

Can I get pg_rewind to show me lost data after a Postgres failover?

Say I have Postgres setup with a warm standby using the build in replication features. Now, imagine a scenario where the data centre the master loses power and the slave is in another data centre and ...
1
vote
1answer
112 views

How to get particular object from jsonb array in PostgreSQL?

I have a field called 'user' that holds a json array that roughly looks like this: "user": [{ "_id" : "1", "count" : "4" }, { "_id" : "3", "count": "4"}] Now I want a query like: select count ...
1
vote
1answer
70 views

Ordering in postgresql

I'm facing an issue whereas I do not understand. Running PostgreSQL on mac and have this query: select tldid, tldaction, to_char(tldactiondate, 'dd/mm/YYYY') as tldactiondate, ...
3
votes
1answer
42 views

Postgres reduce by key if key is not null

I need to select N rows with seq > X which reduce_key is null and for each row group with the same reduce_key select the one with the biggest seq. Result should be strictly sequential (but with ...
0
votes
1answer
26 views

Is it possible to set order in which inherited tables a scanned in postgresql?

I have a postgresql measurement table which is partitioned based on logdate column by month. Suppose I have city_id integer column and want to select latest row with city_id = 125. When I run explain ...
1
vote
0answers
49 views

Three Vital Postgres Columns Corrupted

I run a small website which uses a Postgres database. There are regular back ups based on the amount of traffic we have every few days but there was a recent surge of activity just before a power cut ...
2
votes
0answers
50 views

Insert performance

I am having trouble with Posgresql insert performance. There are 2 tables, documents and words, where documents is essentially a mapping from an external path to a surrogate id, which is foreign ...
1
vote
0answers
21 views

In Postgres, is it possible for me to have a table partitioning constraint based on data type?

Say I have the following schema for my Postgres database: CREATE TABLE sources ( source TEXT NOT NULL, PRIMARY KEY (source) ); CREATE TABLE ipaddrs ( addr INET ) INHERITS (source): CREATE ...
1
vote
1answer
38 views

Disable/enable PostgreSQL trigger inside function for the same table

I have a trigger that protects updating some column. I also have a trigger that should update that same column after insert on that table. I've used triggers like this and it works if I need to update ...
4
votes
2answers
90 views

Understanding a PostgreSQL join

I have seen the following query in the PostgreSQL documentation. Unfortunately I don't understand the join criteria. create temp table tmp_stat_user_tables as select * from pg_stat_user_tables; ...
1
vote
1answer
51 views

Why does this PostGIS query take so long to run?

I am new to PostGIS and SQL in general. I am running a query on polygons which, I hope, only selects distinct geometries and then repair (ST_MakeValid()) those distinct geometries. Thereby removing ...
1
vote
1answer
60 views

Surrogate key resolution, or what am I missing in the Surrogate v Natural argument?

I've read a lot from both camps in the surrogate vs. natural key debate. What I am struggling to understand, and what seems to be glossed over, especially in explaining how surrogate keys are more ...
2
votes
1answer
39 views

Return top 100 words from strings

Not sure this is even possible but I was wondering if there is any way of using PostgreSQL to return the top 100 most occurring words from a database column containing strings of varying lengths? The ...
1
vote
1answer
90 views

Postgres 9.5 foreign table inheritance not using indexes

In PostgreSQL 9.5.0 I have a partitioned table that collects data by months. I tried to use the new PostgreSQL feature of foreign table inheritance and pushed one month of data to another PostgreSQL ...
0
votes
1answer
34 views

PostgreSQL 9.4: Index Only Used For Lower INET Ranges

For some reason queries on the high range of are extremely slow and queries on the low range are extremely fast. My index is an adapted version of the answer in Optimizing queries on a range of ...
0
votes
1answer
76 views

Why are correlated subqueries sometimes faster than joins in Postgres?

This relates to the dataset described in Postgres is performing sequential scan instead of index scan I've started working on adapting the import logic to work with a more normalised schema – no ...
-1
votes
1answer
22 views

in postgres how to select items that have a dupe across two columns

My data looks like this: queryable_type queryable_id User 1 User 2 User 2 I'd like to return dupes so that my result would look like this: queryable_type ...
5
votes
1answer
70 views

How to improve this union to ensure consistent results?

I've been trying to find an reliable and economic way of counting rows over a 7 day period and so far, this is the best I've been able to come up with: Schema CREATE TABLE IF NOT EXISTS "data" ( ...
0
votes
0answers
40 views

Query Postgres table by Block Range Index (BRIN) identifier directly

I have N client machines. I want to load each of machine with distinct partition of BRIN index. That requires to: create BRIN with predefined number of partitions - equal to number of client ...
3
votes
1answer
46 views

What are the limits of Postgresql's large object facility?

I've not found an equivalent of the about PostgreSQL page that covers the limitations of the large object facility in particular, but reading between the lines I think the following is true: No more ...
1
vote
2answers
54 views

Optimising a query to get rows where x is between pairs of values from another table

PostgreSQL 9.4.5 In my database there are 2 tables, vcfentries and exons. I want to query for rows in vcfentries where pos is between a list of pairs of positions, exonstart and exonend in the ...
0
votes
0answers
17 views

Difference between execution times [duplicate]

I managed to make a more efficient my query disabling the sequential scan, but the time in the explain analyze is really different from the real execution of the query, "Execution time: 4854.186 ms" ...
2
votes
2answers
40 views

In Postgres, is it possible to get all rows from a table where a column can be cast to a different type?

I have a table in a Postgres DB that has a TEXT column, named data, that I use to store both IP addresses and domain names. I'm wondering if it's possible to select all the rows in the table whose ...
1
vote
1answer
62 views

Postgres query to return JSON object keys as array

Is it possible to return a JSON object keys as an array of values in PostgreSQL? In JavaScript, this would simply be Object.keys(obj), which returns an array of strings. For example, if I have a ...
4
votes
3answers
494 views

Avoid double query on the same table

I have two queries which are doing basically the same thing, but have different grouping, the first query (query 1) is used to populate a chart, and the second to populate a table. Query 1: SELECT ...