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https://issues.apache.org/jira/browse/GORA-411?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16795698#comment-16795698
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John Mora edited comment on GORA-411 at 3/19/19 5:24 AM:
---------------------------------------------------------
Hi [~alfonso.nishikawa] , [~lewismc].
I would like to work on this issue as a warm up task for my GoSC2019
application.
I added the method _*public*_ _*boolean exists(K key) throws GoraException*_ in
the *DataStore* interface and implemented a default behavior in the
*DataStoreBase* class as follows.
{code:java}
@Override
public boolean exists(K key) throws GoraException {
return get(key,new String [0])!=null;
}
{code}
And, for testing I added the following case:
{code:java}
public static void testExistsEmployee(DataStore<String, Employee> dataStore)
throws Exception {
dataStore.createSchema();
Employee employee = DataStoreTestUtil.createEmployee();
String ssn = employee.getSsn().toString();
dataStore.put(ssn, employee);
dataStore.flush();
assertTrue(dataStore.exists(ssn));
dataStore.delete(ssn);
dataStore.flush();
assertFalse(dataStore.exists(ssn));
}{code}
It seems this naive approach works (tests are passing), so I think I could
analyze every backend in order to find more adequate custom implementations for
each one. But, I would like to know if the test case above is enough for this
new method, do you know other edge cases that should be also checked?.
Cheers,
John
was (Author: jhnmora000):
Hi [~alfonso.nishikawa] , [~lewismc].
I would like to work on this issue as a warm up task for my GoSC2019
application.
I added the method _*public*_ _*boolean exists(K key) throws GoraException*_ in
the *DataStore* interface and implemented a default behavior in the
*DataStoreBase* class as follows.
{code:java}
@Override
public boolean exists(K key) throws GoraException {
return get(key,new String [0])!=null;
}
{code}
And, for testing I added the following case:
{code:java}
public static void testExistsEmployee(DataStore<String, Employee> dataStore)
throws Exception {
dataStore.createSchema();
Employee employee = DataStoreTestUtil.createEmployee();
String ssn = employee.getSsn().toString();
dataStore.put(ssn, employee);
dataStore.flush();
assertTrue(dataStore.exists(ssn));
dataStore.delete(ssn);
dataStore.flush();
assertFalse(dataStore.exists(ssn));
}{code}
It seems this naive approach works (tests are passing), so I think I could
analyze every backend in order to find more adequate custom implementations for
each one. But, I would like to know if the test case above is enough for this
new method, do you know other edge cases that should be also checked?.
Cheers,
John
> Add exists(key) to DataStore interface
> --------------------------------------
>
> Key: GORA-411
> URL: https://issues.apache.org/jira/browse/GORA-411
> Project: Apache Gora
> Issue Type: Improvement
> Components: gora-core, storage
> Reporter: Alfonso Nishikawa
> Priority: Minor
> Fix For: 0.9
>
>
> NUTCH-1679 need to check if there exists some rows and they are proposing to
> use {{store.get(TableUtil.reverseUrl(url)))}}.
> This will have a considerably impact on performance since every column will
> be fetched.
> Some datastores implements a call to just check if a row exists (like HBase)
> so no data is transfered by network.
> If a datastore can't handle an "exists" call, can default to a get.
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