The new per-dictionary settings control regex match semantics around
case sensitivity and the '.' wildcard with newlines. They must be set at
the dictionary level since they're applied to regex engines at
pattern-compile-time.
- regexp_dict_flag_case_insensitive: case insensitive matching
- regexp_dict_flag_dotall: '.' matches all characters including newlines
They correspond to HS_FLAG_CASELESS and HS_FLAG_DOTALL in Vectorscan
and case_sensitive and dot_nl in RE2. These are the most useful options
compatible with the internal behavior of RegExpTreeDictionary around
splitting up simple and complex patterns between Vectorscan and RE2.
The alternative is to use (?i) and/or (?s) for all patterns. However,
(?s) isn't handled properly by OptimizedRegularExpression::analyze().
And while (?i) is, it still causes the dictionary to treat the pattern
as "complex" for sequential scanning with RE2 rather than multi-matching
with Vectorscan, even though Vectorscan supports case insensitive
literal matching. Setting dictionary-wide flags is both more convenient,
and circumvents these problems.
This reverts the following commits:
- e77dd81036
- e8527e720b
Additionally, functional tests are added.
When scanning complex regexp nodes sequentially with RE2, the old code
has an optimization to break out of the loop early upon finding a leaf
node that matches. This is an invalid optimization because there's no
guarantee that it's actually a VALID match, because its parents might
NOT have matched. Semantically, a user would expect this match to be
discarded and for the search to continue. Instead, since we skipped
matching after the first false positive, subsequent nodes that would
have matched are missing from the output value. This affects both
dictGet and dictGetAll.
It's difficult to distinguish a true positive from a false positive
while looping through complex_regexp_nodes because we would have to scan
all the parents of a matching node to confirm a true positive. Trying to
do this might actually end up being slower than just scanning every
complex regexp node, because complex_regexp_nodes is only a subset of
all the tree nodes; we may end up duplicating work with scanning
that Vectorscan has already done, depending on whether the parent nodes
are "simple" or "complex". So instead of trying to fix this
optimization, just remove it entirely.
This function outputs an array of attribute values from all regexp nodes
that matched in a regexp tree dictionary. An optional final argument can
be passed to limit the array size.
Previously due to comparison of floats with doubles, it was incorrectly
works for the upper range:
(lldb) p (float)0.99 > (float)0.99
(bool) $0 = false
(lldb) p (float)0.99 > (double)0.99
(bool) $1 = true
This should also fix performance tests errors on CI:
clickhouse_driver.errors.ServerException: Code: 36.
DB::Exception: default.simple_key_HASHED_dictionary_l0_99: max_load_factor parameter should be within [0.5, 0.99], got 0.99. Stack trace:
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
Right now the memory will be counted for query/user for dictionary, but
only if it load by user (via SYSTEM RELOAD QUERY or via dictGet()), but
it could be also loaded in backgrounad (due to lifetime, or
update_field, so it is like Buffer, only server memory should be
charged.
v2: mark test as long
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
Co-authored-by: Sergei Trifonov <svtrifonov@gmail.com>
In clang-16 the behaviour for POD types had been changed in [1], this
does not allows us to use PackedHashMap for some types.
[1]: 277123376c
Note, that I tried to come up with a more generic solution then
enumeratic types, but failed. Though now I think that this is good,
since this shows which types are not allowed for PackedHashMap
Another option is to use -fclang-abi-compat=13.0 but I doubt it is a
good idea.
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
As it turns out, HashMap/PackedHashMap works great even with max load
factor of 0.99. By "great" I mean it least it works faster then
google sparsehash, and not to mention it's friendliness to the memory
allocator (it has zero fragmentation since it works with a continuious
memory region, in comparison to the sparsehash that doing lots of
realloc, which jemalloc does not like, due to it's slabs).
Here is a table of different setups:
settings | load (sec) | read (sec) | read (million rows/s) | bytes_allocated | RSS
- | - | - | - | - | -
HASHED upstream | - | - | - | - | 35GiB
SPARSE_HASHED upstream | - | - | - | - | 26GiB
- | - | - | - | - | -
sparse_hash_map glibc hashbench | - | - | - | - | 17.5GiB
sparse_hash_map packed allocator | 101.878 | 231.48 | 4.32 | - | 17.7GiB
PackedHashMap 0.5 | 15.514 | 42.35 | 23.61 | 20GiB | 22GiB
hashed 0.95 | 34.903 | 115.615 | 8.65 | 16GiB | 18.7GiB
**PackedHashMap 0.95** | **93.6** | **19.883** | **10.68** | **10GiB** | **12.8GiB**
PackedHashMap 0.99 | 26.113 | 83.6 | 11.96 | 10GiB | 12.3GiB
As it shows, PackedHashMap with 0.95 max_load_factor, eats 2.6x less
memory then SPARSE_HASHED in upstream, and it also 2x faster for read!
v2: fix grower
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
In case you want dictionary optimized for memory, SPARSE_HASHED is not
always gives you what you need.
Consider the following example <UInt64, UInt16> as <Key, Value>, but
this pair will also have a 6 byte padding (on amd64), so this is almost
40% of space wastage.
And because of this padding, even google::sparse_hash_map, does not make
picture better, in fact, sparse_hash_map is not very friendly to memory
allocators (especially jemalloc).
Here are some numbers for dictionary with 1e9 elements and UInt64 as
key, and UInt16 as value:
settings | load (sec) | read (sec) | read (million rows/s) | bytes_allocated | RSS
HASHED upstream | - | - | - | - | 35GiB
SPARSE_HASHED upstream | - | - | - | - | 26GiB
- | - | - | - | - | -
sparse_hash_map glibc hashbench | - | - | - | - | 17.5GiB
sparse_hash_map packed allocator | 101.878 | 231.48 | 4.32 | - | 17.7GiB
PackedHashMap | 15.514 | 42.35 | 23.61 | 20GiB | 22GiB
As you can see PackedHashMap looks way more better then HASHED, and
even better then SPARSE_HASHED, but slightly worse then sparse_hash_map
with packed allocator (it is done with a custom patch to google
sparse_hash_map).
v2: rebase on top of bucket_count fix
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
There are lots of thread pools and simple local-vs-global is not enough
already, it is good to know which one in particular uses threads.
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
