{"id":350,"date":"2007-12-04T09:48:06","date_gmt":"2007-12-04T08:48:06","guid":{"rendered":"http:\/\/soci.hu\/blog\/index.php\/2007\/12\/04\/sql-server-mitoszok\/"},"modified":"2007-12-04T09:48:06","modified_gmt":"2007-12-04T08:48:06","slug":"sql-server-mitoszok","status":"publish","type":"post","link":"https:\/\/soci.hu\/blog\/index.php\/2007\/12\/04\/sql-server-mitoszok\/","title":{"rendered":"SQL Server m\u00edtoszok"},"content":{"rendered":"

Eszembe jutott h\u00e1rom m\u00edtosz, amely gyakran rosszul van implant\u00e1lva az emberek agy\u00e1ba (sok\u00e1ig bel\u00e9m is).<\/p>\n

1. A t\u00e1bla t\u00edpus\u00fa v\u00e1ltoz\u00f3k mem\u00f3ri\u00e1ban laknak. NEM, NEM, NEM. Sajnos sok\u00e1ig \u00e9n is terjesztettem ezt, annak ellen\u00e9re, hogy \u00e1lland\u00f3an ott volt a fejemben, hogy ha nagy a t\u00e1bla, akkor page-elni fog a szerver, amit ut\u00e1l? Nem, a t\u00e1bla t\u00edpus\u00fa v\u00e1ltoz\u00f3 nem m\u00e1s, mint speci\u00e1lis temp t\u00e1bla.
\nB\u0151vebben itt<\/a>. \u00c9rdemes figyelni (\u00e9s kihaszn\u00e1lni) a tranzakcion\u00e1lis k\u00fcl\u00f6nbs\u00e9geket \u00e9s a recompiling viselked\u00e9s k\u00fcl\u00f6nb\u00f6z\u0151s\u00e9g\u00e9t (2005-t\u0151l mondjuk m\u00e1r nem akkora g\u00e1z az \u00fajraford\u00edt\u00e1s az utas\u00edt\u00e1s-szint\u0171 \u00fajraford\u00edt\u00e1s miatt).<\/p>\n

2. A BACKUP DATABASE (full backup) truncate-olja a logot. NEM, NEM, NEM. Ez m\u00e9g valahol logikus is lenne am\u00fagy, hisz minek a log, ha \u00fagyis van full backup, csak az ut\u00e1na k\u00f6vetkez\u0151 log lehet \u00e9rdekes. Nos, itt paranoi\u00e1s m\u00f3don \u00e1lltak a k\u00e9rd\u00e9shez. Ha esetleg elveszne az utols\u00f3 full backup, de m\u00e9g megvan az utols\u00f3 el\u0151tti, \u00e9s a tranzakci\u00f3t se csonkolt\u00e1k, akkor a kett\u0151b\u0151l \u00f6sszerakhat\u00f3 a teljes k\u00e9p.<\/p>\n

3. A TRUNCATE TABLE gyors, de nem visszag\u00f6rgethet\u0151, mert nem logolt m\u0171velet. CSUD\u00c1KAT, NEM! Nem nem logolt, minim\u00e1lisan logolt<\/a>. Csak azt rakj\u00e1k be a logba, hogy mely lapokat \u00e9rintett a m\u0171velet, \u00e9s nem soronk\u00e9nt logolnak, \u00edgy sokkal gyorsabb, mint a delete. De logol, \u00e9s visszag\u00f6rgethet\u0151. Tess\u00e9k kipr\u00f3b\u00e1lni.<\/p>\n","protected":false},"excerpt":{"rendered":"

Eszembe jutott h\u00e1rom m\u00edtosz, amely gyakran rosszul van implant\u00e1lva az emberek agy\u00e1ba (sok\u00e1ig bel\u00e9m is). 1. A t\u00e1bla t\u00edpus\u00fa v\u00e1ltoz\u00f3k mem\u00f3ri\u00e1ban laknak….<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,4,30,21],"tags":[],"class_list":["post-350","post","type-post","status-publish","format-standard","hentry","category-adatbazisok","category-szakmai-elet","category-sql-server","category-sql-server-2005"],"_links":{"self":[{"href":"https:\/\/soci.hu\/blog\/index.php\/wp-json\/wp\/v2\/posts\/350","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/soci.hu\/blog\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/soci.hu\/blog\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/soci.hu\/blog\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/soci.hu\/blog\/index.php\/wp-json\/wp\/v2\/comments?post=350"}],"version-history":[{"count":0,"href":"https:\/\/soci.hu\/blog\/index.php\/wp-json\/wp\/v2\/posts\/350\/revisions"}],"wp:attachment":[{"href":"https:\/\/soci.hu\/blog\/index.php\/wp-json\/wp\/v2\/media?parent=350"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/soci.hu\/blog\/index.php\/wp-json\/wp\/v2\/categories?post=350"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/soci.hu\/blog\/index.php\/wp-json\/wp\/v2\/tags?post=350"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}