-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Dan,
On 12/3/13, 12:32 PM, Daniel Mikusa wrote: > On Dec 3, 2013, at 12:14 PM, Tomcat Random > <tomcat.ran...@gmail.com> wrote: > >> I considered using a validation query but it seemed like extra >> overhead when the default behavior was not, um, behaving in the >> default way. > > The overhead is typically minimal. Running "SELECT 1" or some > other very simply query is not likely to bring your database to > it's knees. It might add a small amount of latency as the pool > will need to execute the query before it give the connection to > your application, but that's likely to be dwarfed by whatever your > application does with the connection after it gets it. > > If you are concerned you can do a couple things to make the process > even more lightweight. > > 1.) With MySQL and use "/* ping */ SELECT 1" as the validation > query. This is a special case with the MySQL JDBC driver that uses > even less resources. +1 We use this everywhere. I've never actually benchmarked it, but since it does not execute a query on the server, it pretty much has to be faster by any measure. > 2.) You can use the tomcat-jdbc connection pool which has a > validationInterval setting. This will ensure that the validation > query is only executed one time during the specified time interval. > I haven't moved to tomcat-pool yet, but this was my initial reaction to Alec's question about usually not needing the validation query. > ...or you can go without a validation query, but it's not something > I would recommend and not something I see done very often. The > minimal overhead is usually worth knowing that you get a valid > connection from the pool. +1 If you don't use a validation query, you need additional try/catch blocks around all your "getConnection()" calls, and a loop to re-try just in case the first connection was bad. I think without a validationQuery, your pool will effectively dry-up over time. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (Darwin) Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCAAGBQJSn236AAoJEBzwKT+lPKRY85sQAMTss/RPDRep+yUhOxCCdCOF 8d2ZhzeDwZ/lM0d+XlH9ZJzbBdwQEpRyZf/uzQRQLK/WO/vReXN3RMptSrN+VoLE TaqWcGva1NPvUOwrMKd1Hm8zKqtcamWTQIHa1MzQ/cN9RChmZbfNwc7CteuTd36C zvXoj1nRhkixfE4jX2/REDtAh0QKQkCj/Dq1BpOlEzJaGwmL/fbwJreUvPiGNvaO xQaCr92Z/Srv32oLCBCu3fs8/FN2KvLKB2YKFWB2iHrRvxiIC7tUWUp9OkZvJga2 ARs7UraFNl/Z+vi8xV2S1cavJD+jeW4ddB5QDr+1yxWRPt0QEE0UzaolATVTUak9 9cRb+87xICd5z/XoFABSPqeicyS/1/cxg/JOHrFtcM8EmXZifB4aVLpnjIqHrRC/ Y3LoCjaIBO78/0i75kC0zeS2opTXMlrvEy/0W/QA8XwGmy7yEvZhbER+TVeHsAcD 6evobH5bbSbnxXgB4o826/ihxMq3JxfZWuaGvCmgB4D4aI0SbtdNP+/SHwirGZA1 Lt/iRCFAGFtJTMygVQZzBn+gbO3mMx7vxesIFbmKRDcUWpQ7MVrs5Wq9mfLUFJp8 YnQS66MM10Nf3O0qNavBN5af4Cq1E+GvcuydchpbDHwd7czkidzLQcGbyIiBpnTq HR5uraaRm89AZ5zUKShW =9ync -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
