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tobenna
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) * fix(aurora): pass formatOptions to Data API Client, fix UUID type support and all other extensions * fix(aurora): refactored the code to avoid duplication (#1) * fix(aurora): refactored the code to avoid duplication
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This type is used instead of a regular EntityManager in the EntityManager.prototype.transaction callback. It extends an EntityManager, so can be used as normal, but is not assignable to one, so functions and services can require this type in order to assert they receive a manager that has already started a transaction
LL specific change - our legacy services use this field to determine if a transaction is active or not, if we don't manage it via typeorm then it's possible legacy clients will still think they are in a transaction when they're not
typeorm currently lets pg.pool assume that clients are always safe to add back into the pool, even if it encountered an error while running a query. this is /usually/ fine, because the vast majority of errors that happen during a query do not cause the client's connection itself to become inoperable however, if, during a query, the client's connection is killed, the query will fail and the client will be placed back into the pool even though it's linked to a now broken connection, i.e. that client will never work again, but because pg.Pool doesn't know that, it'll keep handing it out. end result: lots of failed queries this patches `Connection.prototype.query` so that it passes the error back to the driver when it calls `queryRunner.release`. the driver can (if applicable) then inspect the error and decide if it should result in the client being removed from the pool or just released as normal
we're not confident in our ability to accurately determine what a "bad" error (i.e. one that has rendered the connection broken). to be safe, we'll instruct the pool to remove any client that failed to execute a query though this will result in more pool churn, we're using pgbouncer so those connections are cheap, and this provides maximum safety overall
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Motivation: the query builder (and within it, replacePropertyNames and associated functions) is pretty CPU intensive. For our workload, it's one of the hottest functions in our entire stack. While improved in typeorm#4760, There are still outstanding issues relating to perf e.g. typeorm#3857 As we all know though, the first step in optimization is to measure systematically ;) https://wiki.c2.com/?ProfileBeforeOptimizing On my machine, this benchmark runs in ~3500ms or about 0.35ms/query. This tells us there's a way to go - on my stack, that's about 1/3 of a typical query's latency!
Context: the query builder is pretty CPU intensive, and can be slow - e.g. typeorm#3857 One of the things which makes this slow is `escapeRegExp` in the query builder: we freshly construct the same RegExp once per `replacePropertyName` invocation (many times per overall query!) and since the RegExp itself is constant -- we can lift it out and construct it once. Over-all this saves about 8% on our query build times as measured by typeorm#8955.
Digging further into typeorm#3857. See also typeorm#8955, typeorm#8956. As [previously discussed](typeorm#3857 (comment)), the query builder currently suffers from poor performance in two ways: quadratic numbers of operations with respect to total table/column counts, and poor constant factor performance (regexps can be expensive to build/run!) The constant-factor performance is the more tractable problem: no longer quadratically looping would be a chunky rewrite of the query builder, but we can locally refactor to be a bunch cheaper in terms of regexp operations. This change cuts the benchmark time here in ~half (yay!). We achieve this by simplifying the overall replacement regexp (we don't need our column names in there, since we already have a plain object where they're the keys to match against) so compilation of that is much cheaper, plus skipping the need to `escapeRegExp` every column as a result.
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