SQLite table disk usage

Question

How can I find out the disk usage of a single table inside a SQLite database without copying it in a new empty database?

Answer 1

I realize that this answer totally violates the spirit of the question, but it does get you the size without copying the file...

$ ls -lh db.sqlite
-rw-r--r-- 1 dude bros 44M Jan 11 18:44 db.sqlite
$ sqlite3 db.sqlite
sqlite> drop table my_table;
sqlite> vacuum;
sqlite> ^D
$ ls -lh db.sqlite
-rw-r--r-- 1 dude bros 23M Jan 11 18:44 db.sqlite

Answer 2

It is possible to get details about all the pages used by each table or index from the dbstat table, and it is also possible to aggregate that to get the disk usage of each table or index.

For example, it is possible get the 10 tables using more disk space like this:

sqlite> select name, sum(pgsize) as size from dbstat group by name order by size desc limit 10;

Based on https://www.sqlite.org/dbstat.html

Answer 3

If you are on linux or OSX, or otherwise have the unix utilities awk (and optionally, sort) available, you can do the following to get counts and estimated size via dump analysis:

# substitute '.dump' for '.dump mytable' if you want to limit to specific table
sqlite3 db.sqlite3 '.dump' | awk -f sqlite3_size.awk

which returns:

table            count   est. size
my_biggest_table 1090    60733958
my_table2        26919   7796902
my_table3        10390   2732068

and uses awk script:

/INSERT INTO/ {                              # parse INSERT commands
    split($0, values, "VALUES");             # extract everything after VALUES
    split(values[1], name, "INSERT INTO");   # get tablename
    tablename = name[2];                     #
    gsub(/[\047\042]/, "", tablename);         # remove single and double quotes from name
    gsub(/[\047,]/, "", values[2]);          # remove single-quotes and commas
    sizes[tablename] += length(values[2]) - 3; # subtract 3 for parens and semicolon
    counts[tablename] += 1;
}

END {
    print "table\tcount\test. size"
    for(k in sizes) {
        # print and sort in descending order:
        print k "\t" counts[k] "\t" sizes[k] | "sort -k3 -n -r";

        # or, if you don't have the sort command:
        print k "\t" counts[k] "\t" sizes[k];
    }
}

The estimated size is based on the string length of the "INSERT INTO" command, and so is not going to equal the actual size on disk, but for me, count plus the estimated size is more useful than other alternatives such as page count.

Answer 4

You can use sqlite3_analyzer from https://www.sqlite.org/download.html.

It's a really cool tool. It shows you the number of pages used by each table with and without indexes (each page, by default, is 1024 bytes).

This is a sample sqlite3_analyzer output for the Northwind database:

*** Page counts for all tables with their indices ********************

EMPLOYEES............................. 200         34.4% 
ORDERS................................ 152         26.2% 
CATEGORIES............................ 90          15.5% 
ORDER DETAILS......................... 81          13.9% 
CUSTOMERS............................. 17           2.9% 
SQLITE_MASTER......................... 11           1.9% 
PRODUCTS.............................. 7            1.2% 
SUPPLIERS............................. 7            1.2% 
TERRITORIES........................... 6            1.0% 
CUSTOMERCUSTOMERDEMO.................. 2            0.34% 
CUSTOMERDEMOGRAPHICS.................. 2            0.34% 
EMPLOYEETERRITORIES................... 2            0.34% 
REGION................................ 2            0.34% 
SHIPPERS.............................. 2            0.34% 

It also generates SQL statements which can be used to create a database with usage statistics, which you can then analyze.

Answer 5

I ran into issues with the other answers here (namely sqlite_analyzer not working on Linux). 'Ended up creating the following Bash function to (temporarily) write out each table to disk as a way of assessing the on-disk size. Technically this is copying the db, which is not in the spirit of OP's question, but it gave me the information I was after.

function sqlite_size() {
  TMPFILE="/tmp/__sqlite_size_tmp"
  DB=$1
  IFS=" " TABLES=`sqlite3 $DB .tables`
  for i in $TABLES; do
    \rm -f "$TMPFILE"
    sqlite3 $DB ".dump $i" | sqlite3 $TMPFILE
    echo $i `cat $TMPFILE | wc -c`
    \rm -f "$TMPFILE"
  done
}

Example:

$ sqlite_size sidekick.sqlite
SequelizeMeta 12288
events 16384
histograms 20480
programs 20480