![]() The prototype chain isn’t walked or duplicated.įor more information on Structured clone visit MDN Web Docs.ĭidn’t find what you were looking for? Open a support ticket.For example, if an object is marked readonly with a property descriptor, it will be read/write in the duplicate, since that’s the default. Property descriptors, setters, getters, and similar metadata-like features aren’t duplicated.The lastIndex property of RegExp objects isn’t preserved.Certain object properties aren’t preserved:.Cloning DOM nodes likewise throws a DataCloneError exception.Function objects can’t be duplicated by the structured clone algorithm attempting to throws a DataCloneError exception.When cloning an object, the algorithm recursively traverses through the input object while keeping track of previously visited references in a map to avoid getting stuck in infinite loops. It’s commonly used when invoking structuredClone() or when transferring data between Workers via postMessage(), storing objects with IndexedDB, or copying objects for other APIs. My ONE BIG recommendation - Isolate the table into its own database to avoid issues when performing the exchange as it needs a DBD lock to complete.The structured clone algorithm is a mechanism in JavaScript that can be used to duplicate complex objects. Having worked with CLONE tables for sometime, and got burnt by this one. Enhancements were need to handle Temporal and Archive tables better. FETCH FIRST n ROWS should be used heavily in online or any application that will not Fetch the entire result set. We have predicate push down to each leg, ORDER BY push down to each leg with any FETCH FIRST n ROWS ONLY, with final Sort doing a merge of the sort results. Optimizer team in V12 has given us some enhancements. Queries that UNION are not necessarily as much of an access path problem as they used to be. I had thought of the Clone table with EXCHANGE as an option but not necessarily a good one, as you say. There are many SQL features that need to be used sparingly if at all.įor switching between two tables I quite often see application SQL that has to UNION the two tables and use a switch subquery predicate to decide which of them will actually be queried to find rows. Sorry, we don't need to make serious mistakes at design time. Roger Miller used to say "Don't ask us how it works, tell us your problem, and we will tell you how to fix it." Ha ha, a joke I guess. We therefore need to understand how it works, somewhat. I always say that SQL gives us a lot of rope to hang ourselves, if we don't use it wisely. So a Daily EXCHANGE to switch between 2 tables might not be a great idea, unless have a quiet time. It is quite evident that Exchange is DDL rather than DML to me, so updating the DBD is fairly obvious, and many DDL operations could be risky for contention in operational systems. ![]() I was just adjusting queries on Catalog to Cater for Clone table RTS Stats. If I understood I might recommend against using R.I. Makes it harder to create Indexes (even when Not Unique Defer Yes), without problems, and could interfere with an EXCHANGE Clone too. operations can lock the DBD, even if is a share lock. Yet I was expecting an answer of something moderately obvious, but just was eluding me.ĭBD locks are always an annoying thing to me, except for obviously DDL has to update it. This is maybe the first time, at least in near memory, I ever got a quick and definitive answer to a question that was baffling me. I expected joins to match things rather than deduce by absence or inference that the other instance must be the Clone. ![]() I did not check SYSTABLESPACE again after my Exchange Tables to see that indeed its instance number had switched from 1 to 2. Subject: RE: Clone Table RTS Stats Question. So the RTS supposedly allows space to be monitored on each of 2 tables separately, but perhaps not really, and we just have to add them together?Īre there other situations where 2 instances will both be valid, unrelated to Clones? Initially Clone is likely to be INSTANCE = 2, but after Exchange of data, it is Instance 1, and original table is Instance 2. So how to tell which RTS Instance is the Clone? I could not see anything in the DB2 Catalog to specify it. It can have two entries in SYSTABLESPACESTATS being instance 1 and instance 2, yet SYSTABLESPACE and SYSTABLEPART have one row each (SYSTABLESPACE has INSTANCE=1 only). Geschäftsführung: Gerhard Schubert, Ulf HeinrichĪ Clone Table lives in same UTS as the original table. I simply join the INSTANCE in SYSTABLESPACE to the INSTANCE in the RTS and you are done! As this is the "active" version of the data and obviously, the "other" instance is the "clone" version. ![]() The INSTANCE 2 in the above list were all created by the
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