"
This series adds proper handling of filtering queries with LIMIT.
Previously the limit was erroneously applied before filtering,
which leads to truncated results.
To avoid that, paged filtering queries now use an enhanced pager,
which remembers how many rows dropped and uses that information
to fetch for more pages if the limit is not yet reached.
For unpaged filtering queries, paging is done internally as in case
of aggregations to avoid returning keeping huge results in memory.
Also, previously, all limited queries used the page size counted
from max(page size, limit). It's not good for filtering,
because with LIMIT 1 we would then query for rows one-by-one.
To avoid that, filtered queries ask for the whole page and the results
are truncated if need be afterwards.
Tests: unit (release)
"
* 'fix_filtering_with_limit_2' of https://github.com/psarna/scylla:
tests: add filtering with LIMIT test
tests: split filtering tests from cql_query_test
cql3: add proper handling of filtering with LIMIT
service/pager: use dropped_rows to adjust how many rows to read
service/pager: virtualize max_rows_to_fetch function
cql3: add counting dropped rows in filtering pager
(cherry picked from commit 1afda28cf3)
"
This patchset fixes#3803. When a select statement with filtering
is executed and the column that is needed for the filtering is not
present in the select clause, rows that should have been filtered out
according to this column will still be present in the result set.
Tests:
1. The testcase from the issue.
2. Unit tests (release) including the
newly added test from this patchset.
"
* 'issues/3803/v10' of https://github.com/eliransin/scylla:
unit test: add test for filtering queries without the filtered column
cql3 unit test: add assertion for the number of serialized columns
cql3: ensure retrieval of columns for filtering
cql3: refactor find_idx to be part of statement restrictions object
cql3: add prefix size common functionality to all clustering restrictions
cql3: rename selection metadata manipulation functions
(cherry picked from commit 3fe92663d4)
"
Indexed select statement consists of two queries - the view query
used to extract base keys and the base query that uses those keys
to return base rows.
The main idea of this series is to replace raw proxy.query() call
during the view query to one that uses a pager.
Additionally, paging info from the view query needs to be returned
to the client, in order to be used later for requesting new pages.
"
* 'paging_indexes_7' of https://github.com/psarna/scylla:
tests: add test for secondary index with paging
cql3: remove execute(primary_keys) from select statement
cql3: add incremental base queries to index query
storage_proxy: make get_restricted_ranges public
cql3: add base query handling function to indexed statement
cql3: add generating base key from index keys
cql3: add paging state generation function
cql3: move getting index view schema to prepare stage
pager: make state() defined for exhausted pagers
cql3: add maybe_set_paging_state function
cql3: rename set_has_more_pages to set_paging_state
pager: add setters for partition/clustering keys
cql3: add paging to read_posting_list
cql3: add non-const get_result_metadata method
cql3: make find_index_* functions return paging state
cql3: make read_posting_list return future<rows>
cql3: make pagers use time_point instead of duration
When validating assignment between two types, it's possible one of
them is wrapped in a reverse_type, if it comes, for example, from the
type associated with a clustering column. When checking for weak
assignment the types are correctly unwrapped, but not when checking
for an exact match, which this patch fixes.
Technically, the receiver is never a reversed_type for the current
callers, but this is the morally correct implementation, as the type
being reversed or not plays no role in assignment.
Tests: unit(release)
Fixes#3789
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20180927223201.28152-1-duarte@scylladb.com>
For issue #3362, we will need to add to a materialized view also unselected
base-table columns as "virtual columns". We need these columns to exist
to keep view rows alive, but we don't want the user to be able to see
them.
In this patch we prevent SELECTing the virtual columns of the view,
and also exclude the virtual columns from a "SELECT *" on a view.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Query options may contain bound values needed for checking filtering
restrictions. Previously, empty query_options{} were used, which
caused prepared statements to fail.
Fixes#3677
Original series that introduced filtering logged a warning
when collection restrictions appeared. Instead, an exception
should be thrown until collection restrictions are supported
for ALLOW FILTERING clauses.
Message-Id: <ddaf342d4d6766fadb756f66e5afa0b99ce054f8.1531220558.git.sarna@scylladb.com>
In original series cell iterator for regular cells
was erroneously taken by copy instead of by reference,
which will result in iterating over the first value indefinitely.
Also, the same iterator was not updated for collections,
which is fixed too.
Message-Id: <83297adf8121de4fd37257c87f250d61ea9ec80b.1530892191.git.sarna@scylladb.com>
If any restriction on partition key or static row part fails,
it will be so for every row that belongs to a partition.
Hence, full check of the rest of the rows is skipped.
In order to filter results of an 'ALLOW FILTERING' query,
a visitor that can take optional filter for result_builder
is provided. It defaults to nop_filter, which accepts
all rows.
query::result_view already operates on views of a serialised
query::result. However, until now the value of a cell was always
linearised and copied. This patch makes use of ser::buffer_view to avoid
that.
This commit adds the implementation of SELECT JSON clause
which returns rows in JSON format. Each returned row has a single
'[json]' column.
References #2058
Some code paths were obtaining db_clock timestamp to only convert it
to gc_clock later. Avoid this. In the future we could make gc_clock
cheaper cause it has low precision.
Message-Id: <1482401190-2035-1-git-send-email-tgrabiec@scylladb.com>
Under the hood, the selectable::add_and_get_index() function
deliberately filters out duplicate columns. This causes
simple_selector::get_output_row() to return a row with all duplicate
columns filtered out, which triggers and assertion because of row
mismatch with metadata (which contains the duplicate columns).
The fix is rather simple: just make selection::from_selectors() use
selection_with_processing if the number of selectors and column
definitions doesn't match -- like Apache Cassandra does.
Fixes#1367
Message-Id: <1477989740-6485-1-git-send-email-penberg@scylladb.com>
This is a confusing one, and can be replaced the fact that dense
schemas have a single regular column.
Ref #1542
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
A compact column is a dense schema's single regular column. The fact
that it is a different column_kind has lead to various bugs (#1535,
derived by the schema being dense and the column being regular.
Fixes#1542
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Metadata usually doesn't change after it is created; make that visible in
the code, allowing further optimizations to be applied later.
Message-Id: <1464334638-7971-3-git-send-email-avi@scylladb.com>
We want the format of query results to be eventually defined in the
IDL and be independent of the format we use in memory to represent
collections. This change is a step in this direction.
The change decouples format of collection cells in query results from
our in-memory representation. We currently use collection_mutation_view,
after the change we will use CQL binary protocol format. We use that because
it requires less transformations on the coordinator side.
One complication is that some list operations need to retrieve keys
used in list cells, not only values. To satisfy this need, new query
option was added called "collections_as_maps" which will cause lists
and sets to be reinterpreted as maps matching their underlying
representation. This allows the coordinator to generate mutations
referencing existing items in lists.
In case of schemas that use compact storage it is possible that trailing
components of clustering keys are not set.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
There's no benefit to using C include guards so switch to pragma once
everywhere for consistency.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
To prepare a user-defined type, we need to look up its name in the keyspace.
While we get the keyspace name as an argument to prepare(), it is useless
without the database instance.
Fix the problem by passing a database reference along with the keyspace.
This precolates through the class structure, so most cql3 raw types end up
receiving this treatment.
Origin gets along without it by using a singleton. We can't do this due
to sharding (we could use a thread-local instance, but that's ugly too).
Hopefully the transition to a visitor will clean this up.
This gives about 30% increase in tps in:
build/release/tests/perf/perf_simple_query -c1 --query-single-key
This patch switches query result format from a structured one to a
serialized one. The problems with structured format are:
- high level of indirection (vector of vectors of vectors of blobs), which
is not CPU cache friendly
- high allocation rate due to fine-grained object structure
On replica side, the query results are probably going to be serialized
in the transport layer anyway, so this change only subtracts
work. There is no processing of the query results on replica other
than concatenation in case of range queries. If query results are
collected in serialized form from different cores, we can concatenate
them without copying by simply appending the fragments into the
packet. This optimization is not implemented yet.
On coordinator side, the query results would have to be parsed from
the transport layer buffers anyway, so this also doesn't add work, but
again saves allocations and copying. The CQL server doesn't need
complex data structures to process the results, it just goes over it
linearly consuming it. This patch provides views, iterators and
visitors for consuming query results in serialized form. Currently the
iterators assume that the buffer is contiguous but we could easily
relax this in future so that we can avoid linearization of data
received from seastar sockets.
The coordinator side could be optimized even further for CQL queries
which do not need processing (eg. select * from cf where ...) we
could make the replica send the query results in the format which is
expected by the CQL binary protocol client. So in the typical case the
coordinator would just pass the data using zero-copy to the client,
prepending a header.
We do need structure for prefetched rows (needed by list
manipulations), and this change adds query result post-processing
which converts serialized query result into a structured one, tailored
particularly for prefetched rows needs.
This change also introduces partition_slice options. In some queries
(maybe even in typical ones), we don't need to send partition or
clustering keys back to the client, because they are already specified
in the query request, and not queried for. The query results hold now
keys as optional elements. Also, meta-data like cell timestamp and
ttl is now also optional. It is only needed if the query has
writetime() or ttl() functions in it, which it typically won't have.
