From: Rick James Date: April 20 2012 6:26pm Subject: RE: Why does the limit use the early row lookup. List-Archive: http://lists.mysql.com/mysql/227224 Message-Id: <2E7DD7ADE53B044C8C8BCD9C5829E1EB1485A7D80D@SP2-EX07VS01.ds.corp.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset="gb2312" Content-Transfer-Encoding: base64 QW55IE9SREVSIEJZICh0aGF0IGNhbm5vdCBiZSBkb25lIHVzaW5nIGFuIGluZGV4KSB3aWxsIGdh dGhlciBhbGwgdGhlIGRhdGEgZmlyc3QsIHRoZW4gc29ydCwgdGhlbiBkbyB0aGUgTElNSVQuDQoN ClBvdGVudGlhbCBvcHRpbWl6YXRpb25zIGluY2x1ZGUNCg0KKiBLZWVwIGEgInBvaW50ZXIiLCBu b3QgdGhlIHdob2xlIGRhdGEuICAoVGhpcyBtYXkgYmUgcHJhY3RpY2FsIGZvciBTRUxFQ1QgKiwg YnV0IG5vdCBwcmFjdGljYWwgaW4gb3RoZXIgY2FzZXMuKQ0KDQoqIEJ1aWxkIGEgInByaW9yaXR5 IHF1ZXVlIiB3aXRoIG9ubHkgMTAgaXRlbXMgKGluIHRoZSBjYXNlIG9mIExJTUlUIDEwKS4gIFRo ZSBPUkRFUiBCWSwgaW5zdGVhZCBvZiBkb2luZyBhIHJlZ3VsYXIgc29ydCwgd291bGQgaW5zZXJ0 IGludG8gdGhpcyBxdWV1ZS4gIFRoaXMgX21heV8gYmUgbW9yZSBlZmZpY2llbnQgYmVjYXVzZSBp dCB3b3VsZCBoYXZlIHRvIGhvbGQgb25seSAxMCByb3dzLCBub3QgX2FsbF8gdGhlIHJvd3MuDQoN Cj4gLS0tLS1PcmlnaW5hbCBNZXNzYWdlLS0tLS0NCj4gRnJvbTogUmVpbmRsIEhhcmFsZCBbbWFp bHRvOmgucmVpbmRsQHRoZWxvdW5nZS5uZXRdDQo+IFNlbnQ6IEZyaWRheSwgQXByaWwgMjAsIDIw MTIgMTI6NTAgQU0NCj4gVG86IG15c3FsQGxpc3RzLm15c3FsLmNvbQ0KPiBTdWJqZWN0OiBSZTog V2h5IGRvZXMgdGhlIGxpbWl0IHVzZSB0aGUgZWFybHkgcm93IGxvb2t1cC4NCj4gDQo+IA0KPiAN Cj4gQW0gMjAuMDQuMjAxMiAwNDoyOSwgc2NocmllYiDVxda+uNU6DQo+ID4gTXkgcG9pbnQgaXMg dGhhdCB0aGUgbGltaXQgY2FuIHVzZSBsYXRlIHJvdyBsb29rdXA6IGxvb2t1cCByb3dzIGFmdGVy DQo+ID4gY2hlY2tpbmcgaW5kZXhlcyB0byBvcHRpbWl6ZSB0aGUgc2VsZWN0IHNwZWVkLg0KPiA+ DQo+ID4gQnV0IHRoZSBteXNxbCBvcHRpbWl6ZXIgZG8gaXQgd2l0aCB0aGUgZWFybHkgcm93IGxv b2t1cDogbG9va3VwIGFsbA0KPiA+IHJvd3MgYmVmb3JlIGNoZWNraW5nIGluZGV4ZXMgd2hlbiB0 aGUgb25lIGZldGNoIGNvbHVtbiBpcyBub3QgaW4gdGhlDQo+IGluZGV4ZXMuDQo+ID4NCj4gPiBU ZWxsIG1lIHdoeT8NCj4gDQo+IGJlY2F1c2UgdGhlIG15c3FsIG9wdGltaXplciB1bnRpbCBub3cg aXMgcmVhbGx5IGJhZCBpbiBtYW55IHNpdHVhdGlvbnMNCj4gLSBvcmRlciBieSByYW5kKCkgbWFr ZXMgYSB0ZW1wb3JhcnkgdGFibGUgd2lsIEFMTCBkYXRhIGFzIGV4YW1wbGUgZXZlbg0KPiB3aXRo IGxpbWl0DQo+IA0KPiBzZWxlY3QgKiBmcm9tIHRhYmxlIG9yZGVyIGJ5IHJhbmQoKSBsaW1pdCAx MDsgcmVhZHMgYW5kIHdyaXRlcyB0aGUNCj4gd2hvbGUgdGFibGUgdG8gZGlzayBoYXZlIGZ1biB3 aXRoIGxhcmdlIHRhYmxlcyA6LSkNCg0K