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From: John H. <jh...@im...> - 2011-12-01 21:39:33
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On Thu, 1 Dec 2011, Cefalu, Giuseppa wrote: > Thank you, > > You are correct. Since Squarrel runs with my SQL, all the previous > questions are answered. I guess, my question really is, whether muliple > users can insert, edit and delete records concurrently without > interfearing with each other. In other words, does Squirrel implement > locks to protect the data (data corruption) while users work with the > data concurrenlty? Again, that's the province of the database server. Does MySQL support multiple users inserting, modifying and deleting data concurrently, with appropriate locking and ACID? > I am still confused about Java capabilities. Based on what I know; the > java language does not offer the capability of multiprocess creation > within the application. There is not code to implement myltiprocessing > from inside the application; however; you can write a server for the > application that creates multiple threads bases on user request. When > threads are implemented, the corresponding locks are put in place to > protect data integrity. Multiprocessing in Squirrel would only affect things like being able to run multiple queries in different tabs simultaneously. Proper handling of the effects on data of multiple simultaneous users accessing the data is, again, the province of the database server. > Could you pelase explain a little bit how does Squirell work in this respect? In very broad strokes: 1) a user runs Squirrel 2) ...and opens a database connection 3) ...and types (or loads) a query into the query tab 4) ...and hits [RUN] 5) ...and Squirrel sends the query to the database server via the JDBC interface layer 6) ...where the database server parses and executes the query, retrieving or modifying data 7) ...and sends the results back to Squirrel 8) ...where Squirrel displays the results to the user, in a grid if a dataset was returned. Multiple users can be doing this simultaneously, if the database supports muliple users - which most do these days. ACID and concurrent database access with locking are features of the database server (occurring in step 6 above). They aren't affected by which client application you are using to run queries, whether it's an ad-hoc query tool like Squirrel or a dedicated database application. -- John Hardin KA7OHZ http://www.impsec.org/~jhardin/ jh...@im... FALaholic #11174 pgpk -a jh...@im... key: 0xB8732E79 -- 2D8C 34F4 6411 F507 136C AF76 D822 E6E6 B873 2E79 ----------------------------------------------------------------------- The yardstick you should use when considering whether to support a given piece of legislation is "what if my worst enemy is chosen to administer this law?" ----------------------------------------------------------------------- 14 days until Bill of Rights day |
