Alternatives++.

paper/paper.ms

@@ -1361,7 +1361,10 @@ Isolation : \*[OK] :T{
 technique\*[*]
 T}
 Durability : \*[OK] :\*[OK] checksums
-Access Time : 0.1 to 2ms :a few µs (cache) to a few ms (first access with a hard disk)
+Access Time : 0.1 to 2ms :T{
+a few µs (cache), a few dozen µs (SSD+NVMe), a few hundred µs (SSD)
+and up to a dozen ms (hard disk)
+T}
 High avail. : \*[OK] :T{
 \*[OK] RAID & variants plus many distributed or cluster filesystems
 T}
@@ -1414,11 +1417,15 @@ Beside CRUD operations, a small project could imply basic relations between data
 in DBMS jargon) and a few thousand operations per second.
 Both relations and transactions could be handled by the application, not necessarily by the database system itself.
 .FOOTNOTE2
-Performance is simply not a problem for most use nowadays.
+Performance simply isn't a problem for most uses nowadays.
-Having a directory with a few million entries is fine on modern filesystems.
+Having a directory with a few million entries is fine on modern filesystems since reaching a file by name (with its full path) doesn't trigger a linear search.
-The first file access is slow (a few ms) then the kernel
+The first file access is slow\*[*] then the kernel
 .B automatically
 caches the file, making it reachable in about a few dozen µs which is virtually nothing.
+.FOOTNOTE1
+The first access to a file on a hard drive can be as slow as a few miliseconds and about a hundred microseconds for a SSD.
+But today with the NVMe protocol, the latency to the first file access can be as low as a dozen microseconds.
+.FOOTNOTE2
 .
 .
 .SECTION Alternatives
@@ -1451,7 +1458,18 @@ Sure, DODB doesn't have the same features, but are they worth multiplying the co
 
 .BULLET
 .B "Embedded SQL database" .
-Examples: SQLite and DuckDB.
+Example:
+.B SQLite .
+This is a library (for
+.dq "serverless"
+applications) implementing SQL for database operations, making it far more complex and slower than DODB.
+
+As SQLite, 
+.B DuckDB
+also is a library, with a slightly different objective.
+Instead of being written and optimized to answer real-time requests, the goal is to perform operations on large data sets with a focus on analytical processing.
+And again, as SQLite, DuckDB implements SQL and sophisticated operations making it far more complex than DODB.
+Though, the stated goal is fairly different from the subject of this paper which may explain its complexity.
 
 .BULLET
 .B "New types of SQL" .
@@ -1460,20 +1478,39 @@ Example:
 (modern SQL-like with easy-of-use complex relations),
 .B RethinkDB
 (modern SQL-like, JSON exchanges, distributed).
+These new applications try to improve the SQL language with the benefit of hindsight provided by the experience with current SQL technologies.
+Beside a few simplified operations compared to current SQL equivalent, and some performance improvements thanks to fine-grained typing, none of them tackle the complexity problem of the database itself.
+A new SQL-like language would still require an enormous piece of code to run.
 
 .BULLET
 .B "Key-value stores."
-Examples:
+Example:
-.B RocksDB
-(embedded),
 .B Memcached
-(application to store data cache, not to be used as a primary database system),
+(application to store data cache, not to be used as a primary database system).
-.B CockroachDB
+KV stores are often used as cache for traditional DBMSs.
-(proprietary, distributed, ACID transactions)
+KV stores have the advantage of being simpler than SQL databases, Memcached
+.dq only
+has 61 kloc for example.
 
+However, most KV stores implement features beyond the core functionality.
+.B Redis ,
+and its open-source fork
+.B Valkey ,
+are complex KV stores with a lot of features, including support for many typed data, message broker, clustering, distributed cache, optional durability, server-side scripting, etc.
+
+Many other KV stores can be mentioned, such as
+.B LevelDB
+(embedded),
+and
+.B RocksDB
+(fork of LevelDB with added features, such as transactions, snapshots, bloom filters, optimizations for multi-CPUs, etc.),
+.B CockroachDB
+(proprietary, distributed, ACID transactions), etc.
+
+.KS
 .BULLET
 .B "Document databases" .
-Such as DODB, many other document-oriented databases exist.
+Many other document-oriented databases exist beside DODB.
 For example,
 .B CouchDB
 (distributed, fault-tolerant, RESTful HTTP and JSON API…),
@@ -1481,14 +1518,12 @@ For example,
 (proprietary, ACID transactions, replication…),
 .B UnQlite
 (embedded, ACID transactions, embedded scripting language…).
-
+As far as the author knows, none of them is as simple as DODB.
-.BULLET
+.KE
-.B "Redis"
-
-.BULLET
-.B "duckdb"
 .ENDBULLET
 
+.B Cassandra
+
 .TBD
 .
 .SECTION Future work