Is it possible to query two large tables?

Is it possible to query two large tables?

But if we do this for two very large tables (50m and 150m rows), it would mean a lot of memory being used up for the intermediate hash, as well as a lot of rows from the other candidate being looked up against this hash table. Appropriate indices weren’t being used in the prepared queries.

Why are our queries running so slow in depesz?

We used EXPLAIN ANALYSE and explain.depesz.com to get an idea of the query that was being run. The reason our queries were running so slowly was: In our case, there was a Hash Join taking place, which would create a hash table from rows of one of the candidate tables which match the join predicate.

Why are some of my queries so slow?

As mentioned in a previous post, because of some of our tables growing in size, our queries started performing poorly which resulted in a performance hit to our most used APIs. It was time we revisit some of these queries and do something that will give us the best possible outcome with the least effort.

How to avoid joins on a large table?

Tl;dr: Avoid joins on large tables and evaluate parts of queries beforehand to get 100–10,000x performance gains! As mentioned in a previous post, because of some of our tables growing in size, our queries started performing poorly which resulted in a performance hit to our most used APIs.

What should I know about single table queries?

The chapter then covers other aspects of single-table queries, including predicates and operators, CASE expressions, NULL marks, all-at-once operations, manipulating character data and date and time data, and querying metadata. Many of the code samples and exercises in this book use a sample database called TSQL2012.

What does a table look like in Power Query?

A table is one of those structured values (the others are lists and records) and it is described as „a set of values organized into columns (which are identified by name), and rows.“ Even if tables usually contain columns and rows, they can be empty, which looks like this: #table ( {}, {}).