Fix codegen for binary functions and add fuzz test for math functions
(we need to compile `rusqlite` with `-DSQLITE_ENABLE_MATH_FUNCTIONS` in
order to bundle sqlite with math functions compiled)
Reviewed-by: Jussi Saurio (@jussisaurio)
Closes#1015
Align `substr` implementation with SQLite spec
(https://www.sqlite.org/lang_corefunc.html#substr):
> The substr(X,Y,Z) function returns a substring of input string X that
begins with the Y-th character and which is Z characters long. If Z is
omitted then substr(X,Y) returns all characters through the end of the
string X beginning with the Y-th. The left-most character of X is number
1. If Y is negative then the first character of the substring is found
by counting from the right rather than the left. If Z is negative then
the abs(Z) characters preceding the Y-th character are returned. If X is
a string then characters indices refer to actual UTF-8 characters. If X
is a BLOB then the indices refer to bytes.
Reviewed-by: Jussi Saurio (@jussisaurio)
Closes#1013
According to SQLite documentation, the way to use these instructions
is to compare the seek key to the index key as you would with the
Compare opcode. The compare opcode states:
"Compare two vectors of registers in reg(P1)..reg(P1+P3-1)
(call this vector "A") and in reg(P2)..reg(P2+P3-1) ("B")."
In other words, we should compare the same number of columns from each,
not compare the entire keys.
This fixes a few Clickbench queries returning incorrect results, and
so closes#1009
---
Future work: support index seek keys that use multiple columns. Our
index seek is many times slower than SQLite because we're not utilizing
all the possible columns -- instead we just use the first index column
to seek.
