Governor limits in salesforce

Governor limits are enforced to ensure that code runs correctly without any error. It is necessary to enforce governor limit since apex runs in a multitenant environment, multitenant here simply means a single instance of software runs on a server and serves multiple users at a time. The Apex runtime engine strictly enforces limits to ensure efficient performance.

Some of the important limits are mentioned below.

SOQL queries per transaction → 100(synchronous)

100 Select statement per apex transaction.

SOQL queries per transaction → 200(asynchronous)

200 Select statement per apex transaction.

Number of record retrieve by SOQL query → 50,000

DML statements per transaction → 150

Number of records proceeds by DML statement → 10000

Let's us try to insert more than 10,000 records using DML statement.

List<Account> accList= new List<Account>();

for(integer i = 1; i<20000 ; i++){

Account acc= new Account();

acc.name = 'Test' + '-' + i;

accList.add(acc);

}

insert accList;

EXCEPTION: System.LimitException: Too many DML rows: 10001

STACKTRACE: AnonymousBlock: line 7, column 1

LINE: 7 COLUMN: 1

Total number of SOSL query → 20

Number of record retrieve by SOSL Statement → 2000

Number of future method call per Apex transaction → 50 (synchronous)

Number of future method call per Apex transaction → 0 in batch and future contexts; 50 in queueable context

Number of Apex jobs in queue → 50

Maximum CPU time on the Salesforce servers → 10,000 milliseconds       

Maximum CPU time on the Salesforce servers → 60,000 milliseconds

Maximum execution time for each Apex transaction → 10 mins for both synchronous and asynchronous

Total number of callouts (HTTP requests or web services calls) in a transaction → 100 for both synchronous and asynchronous.

Maximum cumulative timeout for all callouts (HTTP requests or Web services calls) in a transaction → 120 seconds for both synchronous and asynchronous.

Heap size limit → 6 MB ( synchronous)

Heap size limit → 12 MB ( asynchronous)

Note: Refer below article for more details on heap size error and how to avoid it.

SOQL List vs SOQL For Loop

Points to remember to avoid hitting governor limits:

1) Avoid writing for loop inside the method.

2) Use SOQL For Loop instead of a SOQL List For Loop to avoid heap size limit error.

3) Use Test.startTest() method inside test method to reset governor limits.
 
4) Do not update setup objects like user role with other objects in the same transaction.