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Determine Whether Two Date Ranges Overlap
...t these operations in Snodgrass's Developing Time-Oriented Applications in SQL (PDF available online at URL), and in Date, Darwen and Lorentzos Temporal Data and the Relational Model (2002) or Time and Relational Theory: Temporal Databases in the Relational Model and SQL (2014; effectively the seco...
Spark java.lang.OutOfMemoryError: Java heap space
...Hi @samthebest how did you specify 8000 partitions? Since I am using Spark sql I can only specify partition using spark.sql.shuffle.partitions, default value is 200 should I set it to more I tried to set it to 1000 but not helping getting OOM are you aware what should be the optimal partition value ...
Database Design for Revisions?
... should contain all columns present in the first, Records table. E.g. in mysql you can easily create table with the same structure as another table (create table X like Y). And, when you are about to change structure of the Records table in your live database, you have to use alter table commands an...
Can I add a UNIQUE constraint to a PostgreSQL table, after it's already created?
...
psql's inline help:
\h ALTER TABLE
Also documented in the postgres docs (an excellent resource, plus easy to read, too).
ALTER TABLE tablename ADD CONSTRAINT constraintname UNIQUE (columns);
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When to use CouchDB over MongoDB and vice versa
I am stuck between these two NoSQL databases.
7 Answers
7
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Why does this async action hang?
... string connectionString = dataSource.ConnectionString;
// Start the SQL and pass back to the caller until finished
return Task.Run(
() =>
{
// Copy the SQL connection so that we don't get two commands running at the same time on the same open connection
...
How to include “zero” / “0” results in COUNT aggregate?
I've just got myself a little bit stuck with some SQL. I don't think I can phrase the question brilliantly - so let me show you.
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How to do an INNER JOIN on multiple columns
...he above solution and go the following error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'INNER_JOIN airports to_port ON (to_port.code = flights.tairport) WHERE ' at line 7
– Kir...
Export from sqlite to csv using shell script
I'm making a shell script to export a sqlite query to a csv file, just like this:
5 Answers
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What is Scala's yield?
...ndrum - Which interestingly enough is the same order in which the original SQL spec outlines. Somewhere along the way the SQL language inverted the order, but it makes complete sense to first describe what you are pulling from followed by what you expect to get out of it.
– Jo...