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https://issues.apache.org/jira/browse/HBASE-4605?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13140503#comment-13140503
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jirapos...@reviews.apache.org commented on HBASE-4605:
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bq. On 2011-10-29 02:11:25, Gary Helmling wrote:
bq. > Jessie, this looks like a pretty good start. In addition to the
individual comments, a couple of general questions:
bq. >
bq. > 1) Should ConstraintProcessor support some standard way of mapping
Constraint implementations to the families/qualifiers they should apply to?
bq. > 2) Should we ship a base set of Constraint implementations for common
cases?
bq. >
bq. > Even if the answer to both is "yes", they could be addressed as
follow-up JIRAs. But it would be good to think through the end goal here.
bq.
bq. Jesse Yates wrote:
bq. 1) I was thinking an individual constriant could check any/all of the
cf/cq being used. We can do it via (2) where we have an abstract Constraint
that makes it easy to check a given cf/cq.
bq.
bq. So, no (kinda) and yes. For (2), I think it will be community
usage/findings as to what people find useful - we can decide on a case-by-case
basis if it is a valid contribution.
Okay, seems fine to me. Just wanted to raise the questions.
bq. On 2011-10-29 02:11:25, Gary Helmling wrote:
bq. >
src/main/java/org/apache/hadoop/hbase/constraint/ConstraintProcessor.java, line
80
bq. > <https://reviews.apache.org/r/2579/diff/1/?file=53674#file53674line80>
bq. >
bq. > If we use a defined exception class for constraint violations (see
comment above), I think we can omit this try/catch block. Expected exceptions
would already subclass DoNotRetryIOException, so no need to wrap it here.
Other (non-expected) Throwables would be handled higher up by
RegionCoprocessorHost.
bq.
bq. Jesse Yates wrote:
bq. I don't think that runtime exceptions on a constraint should be
allowed to propagate up the CPHost - if the constraint fails then that put
should fail, but not anything else.
Some runtime exceptions could indicate programming errors or bugs, in which
case I think it's best to handle them the same way we handle unexpected errors
in coprocessors -- by either unloading or aborting, depending on configuration.
We need to be careful for what we allow from user code running in process on
region servers.
bq. On 2011-10-29 02:11:25, Gary Helmling wrote:
bq. > src/main/java/org/apache/hadoop/hbase/constraint/IntegerConstraint.java,
line 13
bq. > <https://reviews.apache.org/r/2579/diff/1/?file=53676#file53676line13>
bq. >
bq. > Is this intended as a test class or as a usable implementation? If
a test class, should be under src/test/java/...
bq. >
bq. > If a usable implementation, then, looking at it, I wonder how useful
it is without a way of mapping constraints to individual qualifiers. Do you
think that's something ConstraintProcessor should provide in general?
bq. >
bq. > It could be left up to end user implementations of Constraint to
match which KeyValues they should apply to. But then I don't think any
implementations we can bundle will have much value, unless they provide for
their own qualifier matching via configuration values.
bq.
bq. Jesse Yates wrote:
bq. Its meant to be both an example and a test util. I can move it into
test, but I can see cases where people might want to just check to make sure
they only store values. Yes, it a really simple use case, but it also helps
people to build more complex ones
Maybe it should just go in the documentation then? Either in package level
javadoc or a section of the HBase book? Maybe longer term we need a separate
"examples" maven module for this and other extensions points. But the current
implementation doesn't seem useful out of the box, since it forces integers to
be stored as strings... in order to check that they're integers. Seems odd.
bq. On 2011-10-29 02:11:25, Gary Helmling wrote:
bq. > src/main/java/org/apache/hadoop/hbase/constraint/Constraint.java, line 39
bq. > <https://reviews.apache.org/r/2579/diff/1/?file=53673#file53673line39>
bq. >
bq. > Should we define a base exception here that is thrown? I'm thinking
something like:
bq. >
bq. > ConstraintViolationException extends DoNotRetryIOException
bq. >
bq. > This way we don't need to wrap in DoNotRetryIOException later and we
give implementers a bit more guidance on what to do.
bq.
bq. Jesse Yates wrote:
bq. I wanted to let people throw whatever exception they wanted to so they
can be specific as to what happened with minimal overhead. For instance, the
IntegerConstraint lets the constraint just check to and then throw a
NumberFormatException if it fails. However, the code for the user (the actual
constraint implementation) is super concise and easy.
I disagree here. Treating all possible exceptions the same seems wrong. An
OutOfMemoryError is not equivalent to a NumberFormatException. We need some
structure in place for what types of errors are allowed/expected, instead of
swallowing everything and assuming it's just a constraint violation. I don't
think asking the Constraint implementations to think about what errors they
want to throw is much of a burden.
- Gary
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-----------------------------------------------------------
On 2011-10-31 00:48:49, Jesse Yates wrote:
bq.
bq. -----------------------------------------------------------
bq. This is an automatically generated e-mail. To reply, visit:
bq. https://reviews.apache.org/r/2579/
bq. -----------------------------------------------------------
bq.
bq. (Updated 2011-10-31 00:48:49)
bq.
bq.
bq. Review request for hbase.
bq.
bq.
bq. Summary
bq. -------
bq.
bq. Most of the implementation for adding constraints as a coprocessor.
bq.
bq. Looking for general comments on style/structure, though nitpicks are ok
too.
bq.
bq. Currently missing implementation for disableConstraints() since that will
require adding removeCoprocessor() to HTD (also comments on if this is worth it
would be good).
bq.
bq.
bq. This addresses bug HBASE-4605.
bq. https://issues.apache.org/jira/browse/HBASE-4605
bq.
bq.
bq. Diffs
bq. -----
bq.
bq. src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java 99875b8
bq. src/main/java/org/apache/hadoop/hbase/constraint/BaseConstraint.java
PRE-CREATION
bq. src/main/java/org/apache/hadoop/hbase/constraint/Constraint.java
PRE-CREATION
bq.
src/main/java/org/apache/hadoop/hbase/constraint/ConstraintProcessor.java
PRE-CREATION
bq. src/main/java/org/apache/hadoop/hbase/constraint/Constraints.java
PRE-CREATION
bq. src/main/java/org/apache/hadoop/hbase/constraint/IntegerConstraint.java
PRE-CREATION
bq.
src/test/java/org/apache/hadoop/hbase/constraint/IntegrationTestConstraint.java
PRE-CREATION
bq.
bq. Diff: https://reviews.apache.org/r/2579/diff
bq.
bq.
bq. Testing
bq. -------
bq.
bq. Adding IntegrationTestConstraint and unit tests for Constraints and
IntegerConstraint. All of those pass.
bq.
bq.
bq. Thanks,
bq.
bq. Jesse
bq.
bq.
> Constraints
> -----------
>
> Key: HBASE-4605
> URL: https://issues.apache.org/jira/browse/HBASE-4605
> Project: HBase
> Issue Type: Improvement
> Components: client, coprocessors
> Affects Versions: 0.94.0
> Reporter: Jesse Yates
> Assignee: Jesse Yates
> Attachments: constraint_as_cp.txt, java_Constraint_v2.patch
>
>
> From Jesse's comment on dev:
> {quote}
> What I would like to propose is a simple interface that people can use to
> implement a 'constraint' (matching the classic database definition). This
> would help ease of adoption by helping HBase more easily check that box, help
> minimize code duplication across organizations, and lead to easier adoption.
> Essentially, people would implement a 'Constraint' interface for checking
> keys before they are put into a table. Puts that are valid get written to the
> table, but if not people can will throw an exception that gets propagated
> back to the client explaining why the put was invalid.
> Constraints would be set on a per-table basis and the user would be expected
> to ensure the jars containing the constraint are present on the machines
> serving that table.
> Yes, people could roll their own mechanism for doing this via coprocessors
> each time, but this would make it easier to do so, so you only have to
> implement a very minimal interface and not worry about the specifics.
> {quote}
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