We have been seeing long startup times which disappear spontaneously. During a
restart of the beta cluster, the following goroutine was observed, which suggests
that we were spending a lot of time GCing replicas on startup.

    engine              ??:0                     _Cfunc_DBIterNext(cockroachdb#324, cockroachdb#323, 0, 0, 0, 0, 0, 0, 0)
    engine              rocksdb.go:1135          (*rocksDBIterator).Next(cockroachdb#235)
    storage             replica_data_iter.go:104 (*ReplicaDataIterator).Next(cockroachdb#316)
    storage             store.go:1748            (*Store).destroyReplicaData(#109, cockroachdb#317, 0, 0)
    storage             store.go:841             (*Store).Start.func2(0x101b, cockroachdb#300, 0x36, 0x40, cockroachdb#301, 0x36, 0x40, cockroachdb#315, 0x3, 0x4, ...)
    storage             store.go:734             IterateRangeDescriptors.func1(cockroachdb#306, 0x40, 0x41, cockroachdb#307, 0x92, 0x92, cockroachdb#341, 0, 0x186c, 0x4000, ...)
    engine              mvcc.go:1593             MVCCIterate(cockroachdb#329, #68, #47, #81, cockroachdb#232, 0x9, 0x10, cockroachdb#233, 0xb, 0x10, ...)
    storage             store.go:738             IterateRangeDescriptors(cockroachdb#330, cockroachdb#196, #47, #81, cockroachdb#195, #179, #110)
    storage             store.go:867             (*Store).Start(#109, cockroachdb#330, cockroachdb#196, #179, #185, 0x1)
    server              node.go:405              (*Node).initStores(#78, cockroachdb#330, cockroachdb#196, #98, 0x1, 0x1, #179, 0, #55)
    server              node.go:330              (*Node).start(#78, cockroachdb#330, cockroachdb#196, #42, #129, #98, 0x1, 0x1, 0, 0, ...)
    server              server.go:431            (*Server).Start(#5, cockroachdb#330, cockroachdb#196, #95, 0x1)
    cli                 start.go:368             runStart(#34, #178, 0, 0x9, 0, 0)
    cobra               command.go:599           (*Command).execute(#34, #177, 0x9, 0x9, #34, #177)
    cobra               command.go:689           (*Command).ExecuteC(#33, #70, cockroachdb#343, #72)
    cobra               command.go:648           (*Command).Execute(#33, #71, cockroachdb#343)
    cli                 cli.go:96                Run(#64, 0xa, 0xa, 0, 0)
    main                main.go:37               main()

We have been seeing long startup times which disappear spontaneously. During a
restart of the beta cluster, the following goroutine was observed, which suggests
that we were spending a lot of time GCing replicas on startup.

    engine              ??:0                     _Cfunc_DBIterNext(cockroachdb#324, cockroachdb#323, 0, 0, 0, 0, 0, 0, 0)
    engine              rocksdb.go:1135          (*rocksDBIterator).Next(cockroachdb#235)
    storage             replica_data_iter.go:104 (*ReplicaDataIterator).Next(cockroachdb#316)
    storage             store.go:1748            (*Store).destroyReplicaData(#109, cockroachdb#317, 0, 0)
    storage             store.go:841             (*Store).Start.func2(0x101b, cockroachdb#300, 0x36, 0x40, cockroachdb#301, 0x36, 0x40, cockroachdb#315, 0x3, 0x4, ...)
    storage             store.go:734             IterateRangeDescriptors.func1(cockroachdb#306, 0x40, 0x41, cockroachdb#307, 0x92, 0x92, cockroachdb#341, 0, 0x186c, 0x4000, ...)
    engine              mvcc.go:1593             MVCCIterate(cockroachdb#329, #68, #47, #81, cockroachdb#232, 0x9, 0x10, cockroachdb#233, 0xb, 0x10, ...)
    storage             store.go:738             IterateRangeDescriptors(cockroachdb#330, cockroachdb#196, #47, #81, cockroachdb#195, #179, #110)
    storage             store.go:867             (*Store).Start(#109, cockroachdb#330, cockroachdb#196, #179, #185, 0x1)
    server              node.go:405              (*Node).initStores(#78, cockroachdb#330, cockroachdb#196, #98, 0x1, 0x1, #179, 0, #55)
    server              node.go:330              (*Node).start(#78, cockroachdb#330, cockroachdb#196, #42, #129, #98, 0x1, 0x1, 0, 0, ...)
    server              server.go:431            (*Server).Start(#5, cockroachdb#330, cockroachdb#196, #95, 0x1)
    cli                 start.go:368             runStart(#34, #178, 0, 0x9, 0, 0)
    cobra               command.go:599           (*Command).execute(#34, #177, 0x9, 0x9, #34, #177)
    cobra               command.go:689           (*Command).ExecuteC(#33, #70, cockroachdb#343, #72)
    cobra               command.go:648           (*Command).Execute(#33, #71, cockroachdb#343)
    cli                 cli.go:96                Run(#64, 0xa, 0xa, 0, 0)
    main                main.go:37               main()

**tl;dr** use `\set display_format raw` before a query to get the strings unmodified

Background
----------

One of the inconveniences of SHOW CREATE TABLE is that its output, by
default, encloses the generated CREATE TABLE statement in an ASCII art
table, like this:

````
root@:26257/> SHOW CREATE TABLE t.kv;
+-------+------------------------------------------------+
| Table |                  CreateTable                   |
+-------+------------------------------------------------+
| t.kv  | CREATE TABLE kv (␤                             |
|       |     k INT NOT NULL,␤                           |
|       |     v INT NULL,␤                               |
|       |     CONSTRAINT "primary" PRIMARY KEY (k ASC),␤ |
|       |     FAMILY "primary" (k, v)␤                   |
|       | )                                              |
+-------+------------------------------------------------+
(1 row)
```

This prevents copy-pasting the output directly onto some other
shell or text file.

Meanwhile, our SQL CLI shell *does* provide alternative ways to print
out the results, that can be selected with `\set display_format ...`;
however, none of the formats defined so far are able to print out the
above CREATE TABLE statement **in a way that can be copy-pasted
elsewhere**; for example:

```
root@:26257/> \set display_format html
root@:26257/> SHOW CREATE TABLE t.kv;
<table>
<thead><tr><th>Table</th><th>CreateTable</th></tr></head>
<tbody>
<tr><td>t.kv</td><td>CREATE TABLE kv (<br/>     k INT NOT NULL,<br/>    v INT NULL,<br/>
    CONSTRAINT &#34;primary&#34; PRIMARY KEY (k ASC),<br/>  FAMILY &#34;primary&#34; (k, v)<br/>)</td></tr>
</tbody>
</table>
```

(This replaces all special characters)

```
root@:26257/> \set display_format csv
root@:26257/> SHOW CREATE TABLE t.kv;
1 row
Table,CreateTable
t.kv,"CREATE TABLE kv (
        k INT NOT NULL,
        v INT NULL,
        CONSTRAINT ""primary"" PRIMARY KEY (k ASC),
        FAMILY ""primary"" (k, v)
)"
```

(This escapes the double quotes by doubling them, which renders the SQL invalid)

And so forth.

Solution: new display format
----------------------------

The `cockroach sql` CLI shell (as well as any built-in command that
emits tables) can use a custom display format configurable either with
`--format` on the command-line, or `\set display_format` in the shell.

This patch adds a new format `raw` which causes the string
representation of every record to be printed as-is, starting on its
own line, so that it can be copy-pasted from a terminal.

This format makes an extra mile to ensure the data can be further
processed: each record is prefixed by an annotation of the form `# N`
followed by a newline character, where *N* is the number of characters
in the record, starting with the first character following the
newline. A subsequent automated processing tool can use this
information to determine record boundaries.

Application
-----------

```
root@:26257/> select createtable from [show create table t.kv];
...
CREATE TABLE kv (
        k INT NOT NULL,
        v INT NULL,
        CONSTRAINT "primary" PRIMARY KEY (k ASC),
        FAMILY "primary" (k, v)
)
...
```

Tada!