Don't we first write to WAL and then memstore? Getting confused here, sorry.
JMS Le mer. 7 août 2019 13 h 22, Udai Bhan Kashyap (BLOOMBERG/ PRINCETON) < ukashy...@bloomberg.net> a écrit : > memstore is written first and if write(s) to WAL fails, they are rolled > back. > > From: dev@hbase.apache.org At: 08/07/19 13:15:27To: dev@hbase.apache.org > Subject: Re: does failure of write to memstore has any impact on response > code from hbase > > On Mon, Aug 5, 2019 at 9:36 PM Maneesh Bhunwal <maneesh.bhun...@gmail.com> > wrote: > > > Hi Team, > > > > First fo all thanks for the awesome product. > > > > Can you please help me with how will application behave when write to > > memstore fails but write to WAL has succeeded already,will we return > > success to the user or failure? > > > > Failure. Client will get an exception that varies dependent on failure > type. > > > > Also what if db crashes after writing to WAL, when db will come up after > > crash, it will assume that whatever is there in WAL has been replicated, > > but that may not be the case. > > > > > DB does not make progress until the write to the DB has been sync'd (which > means the edit has been replicated). So on crash, the WAL will be replayed. > The edit that was written to the WAL but not to the memstore on which the > client received an exception, will perpetuate. > > S > > > > Can you please help me with the above? > > > > Regards > > Maneesh Bhunwal > > > > >
