bryder

class TrapInfo {
    # Trap name - eg 18 or 16-1 etc
    $Name
    # if it was checked
    $Done
    # What was found
    $Catch
    # free form notes
    $Notes

bryder

It seems that it does not matter what timezone is on the server as long as you have the time set right for the current timezone, know the timezone of the datetime columns that you store, and are aware of the issues with daylight savings time.

On the other hand if you have control of the timezones of the servers you work with then you can have everything set to UTC internally and never worry about timezones and DST.

Here are some notes I collected of how to work with timezones as a form of cheatsheet for myself and others which might influence what timezone the person will choose for his/her server and how he/she will store date and time.

MySQL Timezone Cheatsheet

bryder

# This is a minor modification of http://stackoverflow.com/a/35483750/1543555

class JSONObjectEncoder(json.JSONEncoder):
    def default(self, obj):
        if hasattr(obj, "to_json"):
            return self.default(obj.to_json())
        else:
            if isinstance(obj, dict):
                return obj
            elif isinstance(obj, datetime.datetime):

bryder

cd ~/.config/google-chrome/Default # or wherever
find . -type f -print0 | xargs --null -n 1 file  |  grep -i sql | cut -d: -f1 | tr '\n' '\0' > /tmp/list
cat /tmp/list | xargs --null -t -n 1 -I'{}' sqlite3 '{}' "PRAGMA integrity_check"

bryder

Lock hints

This is a very nice reference http://big-elephants.com/2013-09/exploring-query-locks-in-postgres/ https://www.postgresql.org/docs/9.3/static/view-pg-locks.html But in essence you want

select * from pg_stat_activity where query like 'DELETE%'; 
select
   locktype, relation:regclass, page, tuple, mode, transactionid as tid, virtualtransaction as vtid, pid, granted

bryder

Types of index scans

Indexes

Sequential Scan:

• Read every row in the table
• No reading of index. Reading from indexes is also expensive.

bryder

List<Object> params = Lists.newArrayList();
if (logger.isDebugEnabled()){
            try {
                PreparedStatement ps = this.getConnection().prepareStatement(q);
                for (int i=0 ; i < params.size(); i++){
                    ps.setObject(i+1, params.get(i));
                }

                logger.debug("Build this {}", ps);

bryder

private interface NameOfInterface {
  public List getAList(Object anArgument);
}

public void useThePassedMethod(NameOfInterface thingToRun) { 
  Integer thing = 1;
  List createdList = thingToRun.getAList(thing);
}

public void callTheThingUsingTheInterface(){

bryder

    private static final org.slf4j.Logger logger =
            org.slf4j.LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());

// When called in a lambda the logger name changed to java.lang.introspection.MethodHandles$lookup 

bryder

 // Using java.lang.reflect  
Field field = instanceOfAClass.getClass().getDeclaredField("nameOfThePrivateVariable");
field.setAccessible(true);
Map<UUID, Long> nameOfThePrivateVariable = (Map<UUID, Long>)field.get(instanceOfAClass);
nameOfThePrivateVariable.put(aNewKey, aNewValue);

// Using org.springframework.test.util.ReflectionTestUtils
// There may be typos in the below! 
Cache<UUID, UUID> aCache = (Cache<UUID, UUID>)ReflectionTestUtils.getField(instanceOfObjectWithCacheAsPrivateField, "aCache");
aCache.invalidateAll();