Is storage space wasted when storing null data?
I am using sqlite database.
When adding records, disk space is obviously used for non-null data. But what about data records containing null values? Why am I asking that I will have a large number of columns (50+) and millions of records that will contain null data while Im wondering if its the most efficient way to design my database.
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In SQLite record format , exactly one byte should indicate what the value is NULL
.
If you normalize your database to have one record per value not NULL
, you keep those NULL
bytes, but you have additional overhead for the values NULL
. Minimum recording on the SQLite : :
- cell pointer with two bytes,
- at least one byte length of the payload,
- multiple bytes for
rowid
and - for your case, a few bytes for a foreign key that points to the original record.
In addition, storing values in a non- NULL
separate table may require an index for efficient searches.
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