073_SFDC Limit

我们在开发的过程中，应多注意一些系统自身的限制，以及遇到此类问题的应对措施：

Description	Synchronous Limit	Asynchronous Limit
Total number of SOQL queries issued1(This limit doesn’t apply to custom metadata types. In a single Apex transaction, custom metadata records can have unlimited SOQL queries.)	100	200
Total number of records retrieved by SOQL queries	50,000
Total number of records retrieved by Database.getQueryLocator	10,000
Total number of SOSL queries issued	20
Total number of records retrieved by a single SOSL query	2,000
Total number of DML statements issued2	150
Total number of records processed as a result of DML statements, Approval.process, or database.emptyRecycleBin	10,000
Total stack depth for any Apex invocation that recursively fires triggers due to insert, update, or delete statements3	16
Total number of callouts (HTTP requests or Web services calls) in a transaction	100
Maximum cumulative timeout for all callouts (HTTP requests or Web services calls) in a transaction	120 seconds
Maximum number of methods with the future annotation allowed per Apex invocation	50
Maximum number of Apex jobs added to the queue with System.enqueueJob	50
Total number of sendEmail methods allowed	Total number of sendEmail methods allowed
Total heap size4	6 MB	12 MB
Maximum CPU time on the Salesforce servers5	10,000 milliseconds	60,000 milliseconds
Maximum execution time for each Apex transaction	10 minutes
Maximum number of push notification method calls allowed per Apex transaction	10
Maximum number of push notifications that can be sent in each push notification method call	2,000