diff options
Diffstat (limited to 'contrib/cube/cube.c')
| -rw-r--r-- | contrib/cube/cube.c | 44 |
1 files changed, 36 insertions, 8 deletions
diff --git a/contrib/cube/cube.c b/contrib/cube/cube.c index dcc0850aa92..d96ca1ec1fd 100644 --- a/contrib/cube/cube.c +++ b/contrib/cube/cube.c @@ -1343,12 +1343,20 @@ g_cube_distance(PG_FUNCTION_ARGS) */ int coord = PG_GETARG_INT32(1); bool isLeaf = GistPageIsLeaf(entry->page); + bool inverse = false; /* 0 is the only unsupported coordinate value */ - if (coord <= 0) + if (coord == 0) ereport(ERROR, (errcode(ERRCODE_ARRAY_ELEMENT_ERROR), - errmsg("cube index %d is out of bounds", coord))); + errmsg("zero cube index is not defined"))); + + /* Return inversed value for negative coordinate */ + if (coord < 0) + { + coord = -coord; + inverse = true; + } if (coord <= 2 * DIM(cube)) { @@ -1376,9 +1384,14 @@ g_cube_distance(PG_FUNCTION_ARGS) /* * For non-leaf we should always return lower bound, * because even upper bound of a child in the subtree can - * be as small as our lower bound. + * be as small as our lower bound. For inversed case we + * return upper bound because it becomes lower bound for + * inversed value. */ - retval = Min(cube->x[index], cube->x[index + DIM(cube)]); + if (!inverse) + retval = Min(cube->x[index], cube->x[index + DIM(cube)]); + else + retval = Max(cube->x[index], cube->x[index + DIM(cube)]); } } } @@ -1386,6 +1399,10 @@ g_cube_distance(PG_FUNCTION_ARGS) { retval = 0.0; } + + /* Inverse return value if needed */ + if (inverse) + retval = -retval; } else { @@ -1542,11 +1559,15 @@ cube_coord(PG_FUNCTION_ARGS) * getter. Moreover, indexed dataset may contain cubes of different dimensions * number. Accordingly, this coordinate getter should be able to return * lower/upper bound for particular dimension independently on number of cube - * dimensions. + * dimensions. Also, KNN-GiST supports only ascending sorting. In order to + * support descending sorting, this function returns inverse of value when + * negative coordinate is given. * * Long story short, this function uses following meaning of coordinates: * # (2 * N - 1) -- lower bound of Nth dimension, - * # (2 * N) -- upper bound of Nth dimension. + * # (2 * N) -- upper bound of Nth dimension, + * # - (2 * N - 1) -- negative of lower bound of Nth dimension, + * # - (2 * N) -- negative of upper bound of Nth dimension. * * When given coordinate exceeds number of cube dimensions, then 0 returned * (reproducing logic of GiST indexing of variable-length cubes). @@ -1560,10 +1581,17 @@ cube_coord_llur(PG_FUNCTION_ARGS) float8 result; /* 0 is the only unsupported coordinate value */ - if (coord <= 0) + if (coord == 0) ereport(ERROR, (errcode(ERRCODE_ARRAY_ELEMENT_ERROR), - errmsg("cube index %d is out of bounds", coord))); + errmsg("zero cube index is not defined"))); + + /* Return inversed value for negative coordinate */ + if (coord < 0) + { + coord = -coord; + inverse = true; + } if (coord <= 2 * DIM(cube)) { |