In the scenario where an operator
* Performs a new crawl from spec
* Doesn't load the data into the index
* Recrawls the data
The recrawl will not find the domains in the database, and the crawl log will be overwritten with an empty file,
irrecoverably losing the crawl log making it impossible to load!
To mitigate the impact similar problems, the change saves a backup of the old crawl log, as well as complains about this happening.
More specifically to this exact scenario however, the parquet-loaded domains are also preemptively inserted into the domain database at the start of the crawl. This should help the DbCrawlSpecProvider to find them regardless of loaded state.
This may seem a bit redundant, but losing crawl data is arguably the worst type of disaster scenario for this software, so it's arguably merited.
Modified the DbCrawlSpecProvider to shuffle domains after loading to ensure a good mix for each crawl. This change prevents overload of crawling the same server in parallel from different subdomains or crawling big domains all at once.
Clean up the sideloading code a bit, making the Reddit sideloader use the more sophisticated SideloaderProcessing approach to sideloading, instead of mimicing StackexchangeSideloader's cruder approach.
The reddit sideloader now uses the SideloaderProcessing class. It also properly sets js-attributes for the sideloaded documents.
The control GUI now also filters the upload directory items based on name, and disables the items that do not have appropriate filenames.
Adds experimental sideloading support for pusshift.io style reddit data. This dataset is limited to data older than 2023, due to licensing changes making large-scale data extraction difficult.
Since the median post quality on reddit is not very good, he sideloader will only load a subset of self-texts and top-level comments that have sufficiently many upvotes. Empirically this appears to mostly return good matches, even if it probably could index more.
Tests were written for this, but all require local reddit data which can't be distributed with the source code. If these can not be found, the tests will shortcircuit as OK. They're mostly there for debugging, and it's fine if they don't always run.
The change also refactors the sideloading a bit since it was a bit messy.
Look at whether the property 'system.conserveProperty' is enabled when deciding he default pool size for the converter.
If true, a much more conservative default is used, limiting the risk of running out of memory.
The WARC specification says the records should transparently remove compression. This was not done, leading to the WARC typically being a bit of a gzip-Matryoshka.
The WARC specification says the records should transparently remove compression. This was not done, leading to the WARC typically being a bit of a gzip-Matryoshka.
This change splits the previous 'repartition' action into two steps, one for recalculating the domain rankings, and one for recalculating the other ranking sets. Since only the first is necessary before the index construction, the rest can be delayed until after...
To avoid issues in handling the shotgun blast of MqNotifications, Service was switched over to use a synchronous message queue instead of an asynchronous one.
The change also modifies the behavior so that only node 1 will push the changes to the EC_DOMAIN database table, to avoid unnecessary db locks and contention with the loader.
Additionally, the change fixes a bug where the index construction code wasn't actually picking up the rankings data.
Since the index construction used to be performed by the index-service, merely saving the data to memory was enough for it to be accessible within the index-construction logic, but since it's been broken out into a separate process, the new process just injected an empty DomainRankings object instead.
To fix this, DomainRankings can now be persisted to disk, and a pre-loaded version of the object is injected into the index-construction process.
The codebase used to have a monkey patched version of gson that made special optimizations for the unusually large JSON files that used to store e.g. crawl data.
Since JSON is no longer used in this fashion, the GSON fork is not needed anymore.
This update enhances the SideloaderProcessing and DocumentClass modules to specially handle sideloaded wiki documents. Wiki content is generally truncated to the first paragraph, which generally tends to be too short to be included independently. An additional DocumentClass (SIDELOAD) has been introduced to suppress the length check in this case.
Wrote a new test to examine the redirect behavior of the crawler, ensuring that the redirect URL is the URL that is reported in the parquet file. This works as intended.
Noticed in the course of this that the crawler doesn't add links from meta-tag redirects to the crawl frontier. Added logic to handle this case, amended the test case to verify the new behavior. Added the meta-redirect case to the HtmlDocumentProcessorPlugin as well, so that we consider it a link between documents in the unlikely case that a meta redirect is to another domain.
The production configuration assumes all content of interest is 7 bit ASCII, and makes a series of optimizations based on this. This assumption holds poorly in the wild.
Adding an **experimental** system property 'system.noFlattenUnicode', that when set to TRUE, will disable this behavior.
IMPORTANT!! The index needs to be re-constructed when this flag is changed, as different hash functions are selected for the keyword->identifier mappings.
The method `isApplicable` in the `PlainTextDocumentProcessorPlugin` was refactored to handle a wider range of content types beyond merely "text/plain". It now also handles any content type that starts with "text/plain;", to accomodate contentTypes that append a charset as well.
Removed the need to have to run an external tool to pre-process the data in order to load stackexchange-style data into the search engine.
Removed the tool itself.
This stirred up some issues with the dependencies, that were due to both third-party:ing xz and importing it as a dependency. This has been fixed, and :third-party:xz was removed.
This commit extracts several previously hardcoded configuration properties, and makes then available through system.properties.
The documentation is updated to reflect the change.
Dead code was also removed in the process. CrawlSpecGenerator is left feeling a bit over-engineered still, since it's built for a more general case, where all other implementations but the current one are removed, but we'll leave it like this for now as it's fairly readable still.
Previously, in order to load encyclopedia data into the search engine, it was necessary to use the encyclopedia.marginalia.nu converter to first create a .db-file. This isn't very ergonomic, so parts of that code-base was lifted in as a 3rd party library, and conversion from .zim to .db is now done automatically.
The output file name is based on the original filename, plus a crc32 hash and a .db-ending, to ensure we can recycle the data on repeat loads.
Use a system.properties file to configure the system. This is loaded statically by MainClass or ProcessMainClass. Update the property names to be more consistent, and update the documentations to reflect the changes.
Several tests were manually running migrations in a large copy-paste blob of code. This makes the test less useful as it's possible to break the code while keeping the tests green by introducing a new migration that never gets run in the tests, and it's also difficult to reason about what the tests are doing.
A new test helper library is introduced with a TestMigrationLoader that can both run Flyway migrations, or load specific migrations in the cases a specific set of migrations need to be loaded. Existing tests are migrated to use the new code.
Add a toggle for saving the WARC data generated by the search engine's crawler. Normally this is discarded, but for debugging or archival purposes, retaining it may be of interest.
The warc files are concatenated into larger archives, up to about 1 GB each.
An index is also created containing filenames, domain names, offsets and sizes
to help navigate these larger archives.
The warc data is saved in a directory warc/ under the crawl data storage.
The changeset also makes the control service responsible for flyway migrations. This helps reduce the number of places the database configuration needs to be spread out. These automatic migrations can be disabled with -DdisableFlyway=true.
The commit also adds curl to the docker container, to enable docker health checks and interdependencies.
The new converter logic assumes that the crawl data is ordered where the domain record comes first, and then a sequence of document records. This is true for the new parquet format, but not for the old zstd/gson format.
To make the new converter compatible with the old format, a specialized reader is introduced that scans for the domain record before running through the sequence of document records; and presenting them in the new order.
This is slower than just reading the file beginning to end, so in order to retain performance when this ordering isn't necessary, a CompatibilityLevel flag is added to CrawledDomainReader, permitting the caller to decide how compatible the data needs to be.
Down the line when all the old data is purged, this should be removed, as it amounts to technical debt.
The EC_DOMAIN_LINK MariaDB table stores links between domains. This is problematic, as both updating and querying this table is very slow in relation to how small the data is (~10 GB). This slowness is largely caused by the database enforcing ACID guarantees we don't particularly need.
This changeset replaces the EC_DOMAIN_LINK table with a file in each index node containing 32 bit integer pairs corresponding to links between two domains. This file is loaded in memory in each node, and can be queried via the Query Service.
A migration step is needed before this file is created in each node. Until that happens, the actual data is loaded from the EC_DOMAIN_LINK table, but accessed as though it was a file.
The changeset also migrates/renames the links.db file to documents.db to avoid naming confusion between the two.
This seems like it would make the wikipedia search result worse, but it drastically improves the result quality!
This is because wikipedia has a lot of articles that each talk about a lot of irrelevant concepts, and indexing the entire document means tangentially relevant results tend to displace the most relevant results.
Modify processingiterator to be constructed via a factory, to enable re-use of its backing executor service.
This reduces thread churn in the converter sideloader style processing of regular crawl data.
Route the sizeHint from the input parquet file to SideloadProcessing, so that it can set sideloadSizeAdvice appropriately, instead of using a fixed "large" number.
This is necessary to populate the KNOWN_URL column in the domain data table, which is important as it is used in e.g. calculating how far to re-crawl the site in the future.
