PolarDB-for-PostgreSQL

1
********************************************************************************
2
Changes that were made in July 2006 by Joshua Reich I.
3
********************************************************************************
4

5
Code Cleanup:
6

7
Update the calling convention for all external facing functions. By external
8
facing, I mean all functions that are directly referenced in cube.sql. Prior
9
to my update, all functions used the older V0 calling convention. They now
10
use V1.
11

12
New Functions:
13

14
cube(float[]), which makes a zero volume cube from a float array
15

16
cube(float[], float[]), which allows the user to create a cube from
17
two float arrays; one for the upper right and one for the lower left
18
coordinate.
19

20
cube_subset(cube, int4[]), to allow you to reorder or choose a subset of
21
dimensions from a cube, using index values specified in the array.
22

23
********************************************************************************
24
Changes that were made in August/September 2002 by Bruno Wolff III.
25
********************************************************************************
26

27
Note that this was based on a 7.3 development version and changes may not
28
directly work with earlier versions.
29

30
I fixed a bug in cubescan.pl that prevented signed numbers with no digits
31
before a decimal point from being accepted. This was submitted as a separate
32
patch and may already be applied.
33

34
cube_inter should really return NULL if the two cubes don't overlap. However
35
this requires changing to the new calling sequence and I don't know enough
36
about how to do it to make the change.
37

38
I changed all floats to doubles except for g_cube_penalty which I don't
39
think can be changed to return double. This might cause the penalty to
40
overflow sooner than one might expect, but overflow could have happened
41
even with floats.
42

43
I changed the output format (in cube_out) to use %.16g instead of %g, since the
44
default is only 6 digits of precision.
45

46
I changed all of the functions declared with (isstrict) to use the current
47
method of declaring this.
48

49
I changed all of the externally visible functions to be immutable which
50
they are. I don't think this matters for the gist functions and didn't
51
try to declare them immutable in case there was something tricky about them
52
that I don't understand.
53

54
I changed the regression tests to use some larger exponents to test output
55
in exponential form. 1e7 was too small for this.
56

57
I added some regression tests to check for 16 digits of precision. This
58
may or may not be a good idea.
59

60
I got rid of the swap_corners function. It created scratch boxes that
61
were iterated through and deleted. This is slower than just getting the
62
larger or smaller coordinate as needed, since swap_corners was doing the
63
same thing with the overhead of a function call and memory allocation.
64

65
I added memset calls to zero out newly allocated NDBOXes as the documentation
66
on functions indicates should be done. This still doesn't allow a hash
67
index for equality since there are multiple representations of the
68
same cube.
69

70
I got rid of a call to cube_same in cube_lt and cube_gt since the test
71
was redundant with other checks being made. The call to cube_same would
72
only be faster if most of the time you were comparing equivalent cubes.
73

74
In cube_lt and cube_gt, the second (UR) for loop for comparing
75
extra coordinates to 0 had the wrong range.
76

77
Note that the cube_distance function wasn't mentioned in the README.cube file.
78

79
I added regression tests for the cube_distance function.
80

81
I added the following new functions:
82
cube
83
cube_dim
84
cube_ll_coord
85
cube_ur_coord
86
cube_is_point
87
cube_enlarge
88

89
cube takes text input and returns a cube. This is useful for making cubes
90
from computed strings.
91

92
cube_dim returns the number of dimensions stored in the data structure
93
for a cube. This is useful for constraints on the dimensions of a cube.
94

95
cube_ll_coord returns the nth coordinate value for the lower left corner
96
of a cube. This is useful for doing coordinate transformations.
97

98
cube_ur_coord returns the nth coordinate value for the upper right corner
99
of a cube. This is useful for doing coordinate transformations.
100

101
cube_is_point returns true if a cube is also a point. This is true when the
102
two defining corners are the same.
103

104
cube_enlarge increases the size of a cube by a specified radius in at least
105
n dimensions. If the radius is negative the box is shrunk instead. This
106
is useful for creating bounding boxes around a point for searching for
107
nearby points. All defined dimensions are changed by the radius. If n
108
is greater than the number of defined dimensions and the cube is being
109
increased (r >= 0) then 0 is used as the base for the extra coordinates.
110
LL coordinates are decreased by r and UR coordinates are increased by r. If a
111
LL coordinate is increased to larger than the corresponding UR coordinate
112
(this can only happen when r < 0) than both coordinates are set to their
113
average.
114

115
I added regression tests for the new functions.
116

117
I added documentation for cube_distance and the new functions to README.cube
118
as well as making a few other minor changes.
119

120
I changed create function to create or replace function in the install
121
script.
122

123
I limited the number of dimensions allowed in cube_enlarge and cube_in
124
to 100 to make it harder for people to mess up the database. The constant
125
is defined in cubedata.h and can be increased if you need something larger.
126

127
I added grant statements to the install script to make the functions
128
executable to everyone.
129

130
Bruno Wolff III <bruno@wolff.to>
131