{"id":55,"date":"2013-09-16T20:45:00","date_gmt":"2013-09-17T01:45:00","guid":{"rendered":"https:\/\/www.chrystalsander.com\/blog\/?p=55"},"modified":"2023-07-26T15:58:50","modified_gmt":"2023-07-26T20:58:50","slug":"linq-query-execution-deferred-vs-immediate","status":"publish","type":"post","link":"https:\/\/www.chrystalsander.com\/blog\/?p=55","title":{"rendered":"LINQ : Query Execution — Deferred vs Immediate"},"content":{"rendered":"
\nA LINQ query can be written to fetch
\nthe results immediately or at a latter point in time. To keep it
\nsimple, LINQ queries are often executed when the query is iterated
\nover (via a foreach loop) — as opposed to when the query variable is
\ncreated. This is considered a \u201cdeferred\u201d execution; however,
\nqueries can also be immediately executed when needed. For example,
\nimmediate execution is useful when the query results need to be
\ncached or re-used.<\/div>\n
\n<\/div>\n
\nFrom a syntax perspective, a query will
\nexecute immediately when the query returns a singleton (Min, Max,
\nCount, Average, etc) or when it ends with .ToList, .ToArray,
\n.ToDictionary, etc.<\/div>\n
\n<\/div>\n
\nDeferred Example:<\/b><\/div>\n
\n<\/div>\n
\npublic<\/span><\/span><\/span> <\/span><\/span><\/span>static<\/span><\/span><\/span> <\/span><\/span><\/span>void<\/span><\/span><\/span> DelayedExecString()<\/span><\/span><\/span><\/div>\n
\n{<\/span><\/span><\/span><\/div>\n
\n       <\/span><\/span><\/span>\/\/Create some data<\/span><\/div>\n
\nstring<\/span><\/span><\/span>[] bikes = <\/span><\/span><\/span>new<\/span><\/span><\/span> <\/span><\/span><\/span>string<\/span><\/span><\/span>[] { <\/span><\/span><\/span>“Yamaha”<\/span><\/span><\/span>, <\/span><\/span><\/span>“Honda”<\/span><\/span><\/span>, <\/span><\/span><\/span>“Ducati”<\/span><\/span><\/span>, <\/span><\/span><\/span>“Suzuki”<\/span><\/span><\/span> };<\/span><\/span><\/span><\/div>\n
\n
<\/span><\/span><\/span><\/div>\n
\n\/\/Build LINQ query<\/span><\/div>\n
\n <\/span>\n<\/div>\n
\nvar<\/span><\/span><\/span> simpleQuery =<\/span><\/span><\/span><\/div>\n
\n    <\/span>from<\/span><\/span><\/span> bike <\/span><\/span><\/span>in<\/span><\/span><\/span> bikes<\/span><\/span><\/span><\/div>\n
\n    <\/span>select<\/span><\/span><\/span> bike<\/span><\/span><\/span><\/div>\n
\n    ;<\/span><\/span><\/span><\/div>\n
\n
<\/span><\/span><\/span><\/div>\n
\n <\/span>\n<\/div>\n
\n\/\/Query is <\/span>NOW <\/b><\/span>executed in a deferred manner<\/span><\/span><\/span><\/div>\n
\nforeach<\/span><\/span><\/span> (<\/span><\/span><\/span>var<\/span><\/span><\/span> type <\/span><\/span><\/span>in<\/span><\/span><\/span> simpleQuery)<\/span><\/span><\/span><\/div>\n
\n{<\/span><\/span><\/span><\/div>\n
\n    <\/span>Console<\/span><\/span><\/span>.WriteLine(<\/span><\/span><\/span>“Bike type is {0}”<\/span><\/span><\/span>, type);<\/span><\/span><\/span><\/div>\n
\n}<\/span><\/span><\/span><\/div>\n
\n\n<\/div>\n
\nConsole<\/span><\/span><\/span>.ReadLine();<\/span><\/span><\/span><\/div>\n
\n
<\/span><\/span><\/span><\/div>\n
\n}<\/span><\/span><\/span><\/div>\n
\n\n<\/div>\n
\nImmediate Example:<\/b><\/div>\n
\n<\/div>\n
\npublic<\/span><\/span><\/span> <\/span><\/span><\/span>static<\/span><\/span><\/span> <\/span><\/span><\/span>void<\/span><\/span><\/span> ImmediateExecString()<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n{<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n       <\/span><\/span><\/span>\/\/Create some data<\/span><\/div>\n
\nstring<\/span><\/span><\/span>[] bikes = <\/span><\/span><\/span>new<\/span><\/span><\/span> <\/span><\/span><\/span>string<\/span><\/span><\/span>[] { <\/span><\/span><\/span>“Yamaha”<\/span><\/span><\/span>, <\/span><\/span><\/span>“Honda”<\/span><\/span><\/span>, <\/span><\/span><\/span>“Ducati”<\/span><\/span><\/span>, <\/span><\/span><\/span>“Suzuki”<\/span><\/span><\/span> };<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n<\/div>\n
\n\/\/Build LINQ query<\/span><\/div>\n
\n <\/span>\n<\/div>\n
\nvar<\/span><\/span><\/span> simpleQuery = (<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n    <\/span>from<\/span><\/span><\/span> bike <\/span><\/span><\/span>in<\/span><\/span><\/span> bikes<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n    <\/span>select<\/span><\/span><\/span> bike).ToList();  <\/span><\/span><\/span>\/\/Query is <\/span>NOW <\/b><\/span>executed immediately<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n
<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n <\/span>\n<\/div>\n
\nforeach<\/span><\/span><\/span> (<\/span><\/span><\/span>var<\/span><\/span><\/span> type <\/span><\/span><\/span>in<\/span><\/span><\/span> simpleQuery)<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n{<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n    <\/span>Console<\/span><\/span><\/span>.WriteLine(<\/span><\/span><\/span>“Bike type is {0}”<\/span><\/span><\/span>, type);<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n}<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n
<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n <\/span>\n<\/div>\n
\nConsole<\/span><\/span><\/span>.ReadLine();<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n
<\/span><\/span><\/span><\/span><\/span><\/div>\n
\n}<\/span><\/span><\/span><\/span><\/span><\/div>\n

<\/p>\n

\n\n<\/div>\n","protected":false},"excerpt":{"rendered":"

A LINQ query can be written to fetch the results immediately or at a latter point in time. To keep it simple, LINQ queries are often executed when the query is iterated over (via a foreach loop) — as opposed to when the query variable is created. This is considered a \u201cdeferred\u201d execution; however, queries … Continue reading “LINQ : Query Execution — Deferred vs Immediate”<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[33],"tags":[83],"_links":{"self":[{"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/55"}],"collection":[{"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=55"}],"version-history":[{"count":1,"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/55\/revisions"}],"predecessor-version":[{"id":244,"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/55\/revisions\/244"}],"wp:attachment":[{"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=55"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=55"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.chrystalsander.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=55"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}