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new 8579143 Update iterators.md (#200)
8579143 is described below
commit 857914353b7b1be5e922c282f667acb7c6f9086c
Author: Mike Miller <mmil...@apache.org>
AuthorDate: Mon Oct 21 12:27:17 2019 -0400
Update iterators.md (#200)
---
_docs-2/development/iterators.md | 18 +++---------------
1 file changed, 3 insertions(+), 15 deletions(-)
diff --git a/_docs-2/development/iterators.md b/_docs-2/development/iterators.md
index cbcd6fe..275331c 100644
--- a/_docs-2/development/iterators.md
+++ b/_docs-2/development/iterators.md
@@ -16,24 +16,13 @@ merge multiple Iterators into a single view. In this sense,
a collection of Iter
a tree-structure than a list, but there is always a sense of a flow of
Key-Value pairs through some Iterators. Iterators
are not designed to act as triggers nor are they designed to operate outside
of the purview of a single table.
-Understanding how TabletServers invoke the methods on a
[SortedKeyValueIterator] can be obtuse as the actual code is
-buried within the implementation of the TabletServer; however, it is generally
unnecessary to have a strong
-understanding of this as the interface provides clear definitions about what
each method should take. This
-chapter aims to provide a more detailed description of how Iterators are
invoked, some best practices and some common
+This guide aims to provide a more detailed description of how Iterators are
invoked, some best practices and some common
pitfalls.
## Instantiation
To invoke an Accumulo Iterator inside of the TabletServer, the Iterator class
must be on the classpath of every
-TabletServer. For production environments, it is common to place a JAR file
which contains the Iterator in
-`lib/`. In development environments, it is convenient to instead place the
JAR file in `lib/ext/` as JAR files
-in this directory are dynamically reloaded by the TabletServers alleviating
the need to restart Accumulo while
-testing an Iterator. Advanced classloader features which enable other types of
filesystems and per-table classpath
-configurations (as opposed to process-wide classpaths). These features are not
covered here, but elsewhere in the user
-manual.
-
-Accumulo references the Iterator class by name and uses Java reflection to
instantiate the Iterator. This means that
-Iterators must have a public no-args constructor.
+TabletServer. It is common to place a JAR file which contains the Iterator in
`lib/`. Accumulo references the Iterator class by name and uses Java reflection
to instantiate the Iterator. This means that Iterators must have a public
no-args constructor.
## Interface
@@ -76,8 +65,7 @@ optimize itself.
### seek
-The `seek` method is likely the most confusing method on the Iterator
interface. The purpose of this method is to
-advance the stream of Key-Value pairs to a certain point in the iteration (the
Accumulo table). It is common that before
+The purpose of the seek method is to advance the stream of Key-Value pairs to
a certain point in the iteration (the Accumulo table). It is common that before
the implementation of this method returns some additional processing is
performed which may further advance the current
position past the `startKey` of the [Range]. This, however, is dependent on
the functionality the iterator provides. For
example, a filtering iterator would consume a number Key-Value pairs which do
not meets its criteria before `seek`
