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<title>SQLite Library Footprint</title>
<tcl>hd_keywords footprint {library size} {relfootprint}</tcl>

<h2 align="center">Size Of The SQLite Library</h2>

The code space used by the SQLite library depends on the target
platform, the compiler, and optimization settings.  These variables
also affect performance.

The chart below shows the relative size and performance for SQLite
as of 2017-10-08 for various compilers and optimization settings
as tested on Ubuntu 16.04.3 on x86_64.  General observations:

The Clang/LLVM compiler is not competitive with GCC.  Clang-generated
binaries are consistently larger and slower than GCC-generated binaries.

Profile guided optimization (PGO) is not helpful with SQLite.  PGO results
in binaries that are about 1% larger and about 0.33% slower.

GCC-7 generates binaries that are smaller and faster than GCC-5, though
the difference is not that great.

Compiling with GCC and -Os results in a binary that is slightly less 
than 500KB in size.

The only significant design decision that developers need to make is
whether to use -Os (optimize for size) or -O6 (optimize for speed).
The -O6 setting makes binaries that run about 2% or 3% faster, but which
are also 66% larger.  The performance here is measured by counting CPU
cycles using cachegrind.  I-cache misses are not considered in the
analysis.  If I-cache misses are considered, builds with -O6 might not
be any faster than builds with -Os.

Taking into consideration all of the above, the SQLite developers recommend
compiling SQLite using GCC-7 with the -Os optimization setting.

<img src='images/cc-diff.jpg'>


Measurements above were conducted using SQLite version 
[|5594a121bf132a98] from

The only SQLite compile-time option used was [-DSQLITE_ENABLE_MEMSYS5].
The optional [memsys5] memory allocator is used for performance testing
because it gives results that are more repeatable than the library-supplied
malloc()/free() on Ubuntu.

Performance can be improved and the size reduced by
All these options together result in about a 3.5% performance increase and
a 3.0% size reduction.

Adding optional features like [-DSQLITE_ENABLE_JSON1],
[-DSQLITE_ENABLE_FTS5], or [-DSQLITE_ENABLE_RTREE] will increase the
size of the library, obviously.

Performance was measured using the
[|speedtest1.c] utility program,
which attempts to mimic a typical workload for SQLite.  Options to
the test runs are:
<tt>--shrink-memory --reprepare --stats --heap 10000000 64 --size 5</tt>
Performance was measured by running speedtest1 using cachegrind and
observing the "I refs" output.