sql - When is it appropriate to use NOLOCK? -


I have periodical problems and deadlock coming from time to time with questions that last a few minutes.

I am thinking that when using NOLOCK is most appropriate and where?

Do I update it & amp; Inserts? Or reads? Note that you can specify nolock on each table basis.

I usually used nolock in complex selection choices, but only for small viewing tables, which almost never changed, and for display-only data. You know the tables that list the current half year prices, or the look strings of the id etc. Goods that change with major updates, after which the server usually restarts regularly on a regular basis.

This improved performance, at the busiest time, reduced the chance of stagnation, and more importantly it was not really important during moments of many cases, which touched many tables (which is rational , They have to get less locks, and those sidetables are often used everywhere, often 7-8 to 4 tables are lacking which must be locked)

But it is very careful to add it are Do not hurry it, and do not do it regularly, it will not hurt if used properly, but it will hurt if used incorrectly.

Do not use it for the most important stuff, the stuff that counts, etc., because it will become inconsistent, whatever happens quickly or later.

Another such customization is ROWLOCK, which locks only at the row level This is mainly useful when updating tables (or deletion), where the rows are not related to each other, Like in tables where you only put in log records (and in whatever order they are involved there is no such thing). If you have a plan that, at the end of a transaction, a log record is written in some table, it can be much faster.

If your database writes a relatively small percentage, then it is not possible to do this. <2 p>


Comments

Post a Comment

Popular posts from this blog

python - Overriding the save method in Django ModelForm -

I'm having trouble overriding a ModelForm save method. I get this error I'm: Exception type: TypeErier Exception Value: Save () found an unexpected keyword argument 'committed' My intentions include a form 3 fields Submit several values ​​for, then create an object for each combination of those areas, and to save each object file models.py class collarsult type (models.Model): id = model. AutoField (db_column = 'icontact_result_code_type_id', primary_key = true) callResult = models.ForeignKey ( 'CallResult', db_column = 'icontact_result_code_id') campaign = models.ForeignKey ( 'campaign', db_column = 'icampaign_id') CALLTYPE = models.ForeignKey ( 'CALLTYPE', db_column = 'icall_type_id') agent = models.BooleanField (db_column = 'bagent', default = true) teamLeader = models.BooleanField (db_column = 'bTeamLeader', default = true) active = models.BooleanField (db_column = Django.form...
Read more

html - CSS autoheight, but fit content to height of div -

I have a div in which there are three children- div in the left and middle div: float: left while true: float: true because it is my layout Actually will spoil, I've used ClearFix Hack: .cf {zoom: 1; }. Cf: First,. Cf: {content: ""; Display: Table; }. Cf: After {clear: both; } It still works, but I want to be the right div an indicator. So it should fill 100% of the parent unit of height. How can I complete this? PS is the full code: & Lt; / Div & gt; & Lt; Div class = "mobile_content" & gt; & Lt; H5 & gt; {{Data.titel}} & lt; / H5> & Lt; Table & gt; & Lt; TR & gt; & Lt; Th & gt; Komponist: & lt; / Th & gt; & Lt; TD & gt; {{Data.komponist}} & lt; / TD & gt; & Lt; / TR & gt; & Lt; TR & gt; & Lt; Th & gt; Instrument: & lt; / Th & gt; & Lt; TD & gt; {{Data.instrumente}} & lt; / TD & gt; & Lt; / TR & gt;...
Read more

qt - How to prevent QAudioInput from automatically boosting the master volume to 100%? -

I have been trying to use Qt5 multimedia to record audio with QAudioInput, however, when I see If QAudioInput is started, it increases the master volume of my sound device to 100%. How can I prevent QAudioInput from changing the master volume? My current development platform is Linux with PalsAdio (with flat audio disabled). How can I use QAudioInput : QAudioDeviceInfo device_info = QAudioDeviceInfo :: defaultInputDevice (); QAudio format format; Format.setSampleRate (44100); Format.setChannelCount (1); Format.setSampleSize (16); Format.setCodec ("Audio / PCM"); Format.setSampleType (QAudioFormat :: SignedInt); Format.setByteOrder (QAudioFormat :: LittleEndian); Std :: cout & lt; & Lt; Device_info.deviceName (). ToUtf8 (). ConstData () & lt; & Lt; Std :: endl; QAudioInput * default_device = new QAudioInput (device_info, format); QIODevice * default_io_device = default_device-> Start (); a QAudioInput.setVolume () method is not you I ...
Read more