This commit adds a function that compares split mutations with the
`row_state`, that was selected as a preimage or propagated through
cdc options by a caller. If the items are equal, the corresponding log
row isn't generated. The result being that creating an item with
BatchWriteItem, PutItem, or UpdateItem doesn't emit an INSERT/MODIFY
event if exactly identical item already exists.
Comparing the items may be costly, so this logic is controlled by
`alternator_streams_compabitiblity` flag.
This commit handles the following cases:
- `PutItem/UpdateItem/BatchWriteItem.PutItem of an existing and equal
item: nothing`
CDC log table records a mutation as a sequence of log rows that record
an atomic change (i.e. a row marker, tombstones, etc.), whereas a
mutation in Alternator Streams always appears as a single log row. The
type of operation is determined based on the type of the last log row in
CDC.
As a result, updates that create a row always appeared to Alternator
Streams as an update (row marker + data), rather than an insert. This
commit makes them a single log row. Its operation type is insert if it
contains a row marker, and an update otherwise, which gives results
consistent with DynamoDB Streams.
As requested in #22104, moved the files and fixed other includes and build system.
Moved files:
- combine.hh
- collection_mutation.hh
- collection_mutation.cc
- converting_mutation_partition_applier.hh
- converting_mutation_partition_applier.cc
- counters.hh
- counters.cc
- timestamp.hh
Fixes: #22104
This is a cleanup, no need to backport
Closesscylladb/scylladb#25085
Schema related files are moved there. This excludes schema files that
also interact with mutations, because the mutation module depends on
the schema. Those files will have to go into a separate module.
Closes#12858
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
The database, keyspace, and table classes represent the replica-only
part of the objects after which they are named. Reading from a table
doesn't give you the full data, just the replica's view, and it is not
consistent since reconciliation is applied on the coordinator.
As a first step in acknowledging this, move the related files to
a replica/ subdirectory.
Fixes#7435
Adds an "eor" (end-of-record) column to cdc log. This is non-null only on
last-in-timestamp group rows, i.e. end of a singular source "event".
A client can use this as a shortcut to knowing whether or not he has a
full cdc "record" for a given source mutation (single row change).
Closes#7436
In some cases, tracking the state of processed rows inside `transformer`
is not needd at all. We don't need to do it if either:
- Preimage and postimage are disabled for the table,
- Only preimage is enabled and we are processing the last timestamp.
This commit disables updating the state in the cases listed above.
Introduces new methods to the change_processor interface that will cause
it to produce pre/postimage rows for requested clustering key, or for
static row.
Introduces logic in split.cc responsible for calling pre/postimage
methods of the change_processor interface. This does not have any effect
on generated CDC log mutations yet, because the transformer class has
empty implementations in place of those methods.
This allows for a more refined use of the transformer by the
for_each_change function (now named "process_changes_with_splitting).
The change_processor interface exposes two methods so far:
begin_timestamp, and process_change (previously named "transform").
By separating those two and exposing them, process_changes_with\
_splitting can cause the transformer to generate less CDC log mutations
- only one for each timestamp in the batch.
If a batch update is performed with a sequence of changes with a single
timestamp, they will now show up in CDC with a single timeuuid in the
`time` column, distinguished by different `batch_seq_no` values.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
`for_each_change` is like `split` but it doesn't return a vector of
mutations representing each change; instead, it takes as a parameter
a function which gets called on each mutation.
This reduced the memory usage and allows to preserve common context
when handling each change (will be useful in next commits).
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
The function checks if there are multiple timestamps and/or ttls inside
a mutation, which means separate changes should be created for this
mutation in CDC.
