Couchbase substring function is 0-based

SELECT SUBSTRING('49',1)

SELECT SUBSTRING(IntKey,1) FROM BQT1.SmallA WHERE IntKey=49

16:04:32,385 INFO  [org.teiid.COMMAND_LOG] (New I/O worker #2) QE2ZpDa/Btt5     START USER COMMAND: startTime=2017-08-24 16:04:32.385       requestID=QE2ZpDa/Btt5.116    txID=null sessionID=QE2ZpDa/Btt5        applicationName=JDBC          principal=user@teiid-security vdbName=couchbase   vdbVersion=1        sql=SELECT SUBSTRING(IntKey,1) FROM BQT1.SmallA WHERE IntKey=49
16:04:32,390 DEBUG [org.teiid.COMMAND_LOG] (Worker35_QueryProcessorQueue325) QE2ZpDa/Btt5           START DATA SRC COMMAND:       startTime=2017-08-24 16:04:32.39        requestID=QE2ZpDa/Btt5.116    sourceCommandID=0   executionID=79      txID=null modelName=Couchbase_small     translatorName=couchbase      sessionID=QE2ZpDa/Btt5        principal=user@teiid-security sql=SELECT SUBSTRING(convert(Couchbase_small.SmallA.IntKey, string), 1) FROM Couchbase_small.SmallA WHERE Couchbase_small.SmallA.IntKey = 49
16:04:32,391 DEBUG [org.teiid.COMMAND_LOG] (Worker35_QueryProcessorQueue325) QE2ZpDa/Btt5           SOURCE SRC COMMAND: endTime=2017-08-24 16:04:32.391         requestID=QE2ZpDa/Btt5.116    sourceCommandID=0   executionID=79      txID=null modelName=Couchbase_small     translatorName=couchbase      sessionID=QE2ZpDa/Btt5        principal=user@teiid-security sourceCommand=[SELECT SUBSTR(TOSTRING(`$cb_c1_IntKey`), 1) FROM `dvqe_small` `$cb_t1` LET `$cb_c1_IntKey` = `$cb_t1`.`IntKey` WHERE `$cb_c1_IntKey` = 49 AND `$cb_t1`.`type` = 'SmallA'] 
16:04:32,607 DEBUG [org.teiid.COMMAND_LOG] (Worker34_QueryProcessorQueue326) QE2ZpDa/Btt5           END SRC COMMAND:    endTime=2017-08-24 16:04:32.607         requestID=QE2ZpDa/Btt5.116    sourceCommandID=0   executionID=79      txID=null modelName=Couchbase_small     translatorName=couchbase      sessionID=QE2ZpDa/Btt5        principal=user@teiid-security finalRowCount=1     cpuTime(ns)=1689816
16:04:32,610 INFO  [org.teiid.COMMAND_LOG] (Worker34_QueryProcessorQueue327) QE2ZpDa/Btt5           END USER COMMAND:   endTime=2017-08-24 16:04:32.61          requestID=QE2ZpDa/Btt5.116    txID=null sessionID=QE2ZpDa/Btt5        principal=user@teiid-security vdbName=couchbase   vdbVersion=1        finalRowCount=1