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The data in indexes is stored columnar by most RDBMSes, as far as I know.
by Denvercoder9 4y ago
The data in indexes is stored columnar by most RDBMSes, as far as I know.
- ddorian43 4y agoIt actually is not.
- janwas 4y agoI don't know about "most", but here is a list: https://en.wikipedia.org/wiki/List_of_column-oriented_DBMSes https://en.wikipedia.org/wiki/List_of_column-oriented_DBMSes
- ComputerGuru 4y agoNo, this is a list of columnar database systems - gp was saying the index, which is often (but not always) stored separately from the main db records.
- janwas 4y agoAh, indeed, my mistake. FWIW I've observed increasing numbers of papers over the past couple of years mentioning entirely columnar databases.
- wenc 4y agoTypically a rowstore index is a B-tree data structure (on a column) that points to data pages in a rowstore dataset. It's not technically columnar as such. You can sort with a rowstore index today, but I imagine you have to materialize the index in some way to take advantage of vectorization.
- kjeetgill 4y agoI mean, I guess you could call a B-Tree over a subset of columns "columnar"... And bit-map indexes are by columns too — but that's really bending the definition of what most people mean by columnar storage in databases.